Management conditions configuration when the secondary cell is unavailable

Abstract

The processing hardware in the user equipment (UE) can implement methods for managing mobility. These methods include operation in dual connectivity (DC) via a primary cell and primary node (MN) and via a primary-secondary cell and secondary node (SN), with the MN and SN operating within a radio access network (RAN) (1702). The methods also include receiving from the RAN conditional configurations associated with candidate primary and secondary cells, which are linked to conditions to be satisfied by the UE before applying the conditional configurations during a conditional procedure (1704). The methods further include detecting a secondary cell group (SCG) failure. Furthermore, the methods include suspending the conditional procedure in response to this detection.

Description

[0001] This disclosure generally relates to wireless communications, and more specifically, to management condition configuration when a user equipment (UE) operates in multiple radio dual connectivity (MR-DC) and encounters a secondary cell group configuration (SCG) failure. Background Technology

[0002] This background description is provided to provide an overall context 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 otherwise not conform to the prior art at the time of filing are neither explicitly nor implicitly considered to be prior art of this disclosure.

[0003] 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 the 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.

[0004] UEs can use several types of SRBs and DRBs. When operating in dual connectivity (DC), the cell associated with the base station of the operating primary node (MN) defines the primary cell group (MCG), and the cell associated with the base station of the operating 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, also on the DCCH but with a lower priority than the SRB1 resource, including recorded measurement information or NAS messages. More generally, the SRB1 and SRB2 resources allow the UE and MN to exchange MN-related RRC messages and embedded SN-related RRC messages, and can also be referred to as MCG SRBs. The SRB3 resource allows the UE and SN to exchange SN-related RRC messages and can also be referred to as SCG SRBs. Separate 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 MCG or both SCG can be called a split DRB.

[0005] 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 connectivity 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), and another base station operates as the secondary node (SN) covering the primary secondary cell (PSCell). The UE communicates (via the PCell) with the MN and (via the PSCell) with the SN. 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 procedure.

[0006] 3GPP Technical Specifications (TS) 36.300 and 38.300 describe procedures for handover scenarios (also known as reconfiguration with synchronization). These procedures involve message passing between RAN nodes that typically results in delays (e.g., RRC signaling and preparation), which in turn increases the probability of handover procedures. These procedures do not involve conditions associated with the UE and may be referred to as “immediate” handover procedures. R2-1914640 and R2-1914834 describe procedures for conditional handover scenarios.

[0007] 3GPP specification TS 37.340 (v15.7.0) describes procedures for UEs to add or change SNs in DC scenarios. These procedures involve message passing between radio access network (RAN) nodes (e.g., RRC signaling and preparation). Such message passing typically results in latency, which in turn increases the likelihood that the SN addition or SN change procedure will fail. These procedures (which do not involve conditions checked at the UE) can be referred to as “on-demand” SN addition and SN change procedures.

[0008] Whether operating in Single Connectivity (SC) or DC, the UE can also perform a handover procedure to switch from one cell to another. Depending on the scenario, the UE can hand over from a cell of a first base station to a cell of a second base station, or from a cell of a first Distributed Unit (DU) of a base station to a cell of a second DU of the same base station. 3GPP specifications 36.300v15.6.0 and 38.300v15.6.0 describe a handover procedure that includes several steps (RRC signaling and preparation) between RAN nodes. These steps can cause latency in the handover procedure and thus increase the risk of handover failure. This procedure (which does not involve conditions checked at the UE) can be referred to as an "on-demand" handover procedure.

[0009] Recently, "conditional" procedures (i.e., conditional SN or PSCell addition / modification and conditional handover) have been considered for SN or PSCell addition / modification and handover. Unlike the "immediate" procedures discussed above, these procedures do not add or modify 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 exceeds 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.).

[0010] To configure the conditional procedure, the RAN provides the UE with conditions and configuration (e.g., a set of 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. For example, for the conditional addition of a base station as an SN or a candidate cell as a PSCell, the RAN provides the UE with the conditions that must be met before the UE can add the base station as an SN or the candidate cell as a PSCell, and the configuration that enables the UE to communicate with the base station or PSCell after the conditions are met.

[0011] In some cases, a UE operating in MR-DC can detect secondary cell group (SCG) failure as described in 3GPP specifications 36.331v15.8.0 and 38.331v15.8.0. Generally, SCG failure prevents the UE from communicating with the SN, at least temporarily. When the UE also has conditional configurations associated with candidate PSCells, it is unclear how the UE and / or base station should manage these conditional configurations when the UE detects an SCG failure. When the state of the conditional configurations is not precisely defined, the base station operating as the SN may fail to recognize the UE, or the base station may fail to release resources in a timely manner. Summary of the Invention

[0012] The UE disclosed herein initially operates in a DC with an MN and an SN. In some scenarios, the UE detects an SCG failure and receives conditional configuration related to the C-PSCell either before or after the SCG failure is detected. In other scenarios, the UE receives conditional configuration related to the C-PSCell, attempts to connect to the C-PSCell, but fails to complete the random access procedure. The UE determines whether it should retain the conditional configuration and subsequently attempts to resume communication in the DC via the PSCell or the C-PSCell.

[0013] In some implementations, the UE retains the conditional configuration after detecting an SCG failure and attempts to resume communication in the DC via the C-PSCell. According to some of these implementations, the UE applies the conditional configuration only if the corresponding condition is met. However, in other cases, the UE applies the conditional configuration regardless of whether the corresponding condition is met, if the C-PSCell is suitable. In other implementations, the UE releases the conditional configuration after detecting an SCG failure and subsequently receives a reconfiguration command for connecting to the SN via a new PSCell.

[0014] An example embodiment of the technology disclosed herein is a method for managing mobility in a UE that operates in a DC via a primary cell and an MN and via a primary / secondary cell and an SN, the MN and SN operating in a RAN. The method is implemented by processing hardware and includes receiving conditional configurations associated with candidate primary / secondary cells from the RAN. These conditional configurations are associated with conditions to be satisfied by the UE before applying the conditional configurations during a conditional procedure. The method also includes detecting communication failures via the primary / secondary cell or candidate primary / secondary cells. Furthermore, the method includes determining, at least in part, the configuration upon which the UE will recover the DC based, based on the failure.

[0015] Another example embodiment of these technologies is a UE that includes processing hardware and is configured to perform the methods described above.

[0016] Another example embodiment of these technologies is a method for configuring a UE in a RAN. This method is implemented by processing hardware and includes communicating with the UE via the primary cell of the MN and the primary / secondary cell of the SN to provide a DC to the UE. The method also includes sending a conditional configuration associated with a candidate secondary cell to the UE by the processing hardware, the conditional configuration being associated with conditions to be met by the UE before applying the conditional configuration during a conditional procedure. The method further includes suspending communication with the UE via the SN in response to determining that communication between the UE and the secondary cell or candidate secondary cell has failed. Furthermore, the method includes resuming communication with the UE via the SN. Attached Figure Description

[0017] 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 disclosed herein for managing conditional procedures associated with a master node (MN) or a secondary node (SN);

[0018] Figure 1B This is another block diagram of an example system in which the radio access network (RAN) and user equipment can implement the techniques disclosed herein for managing conditional procedures related to the MN or SN;

[0019] Figure 1C Among them, centralized units (CU) and distributed units (DU) can be Figure 1A or Figure 1B A block diagram of an example base station operating in the system;

[0020] Figure 2 yes Figure 1A A block diagram of an example protocol stack used by the UE to communicate with the base station;

[0021] Figure 3A This is a message passing diagram of an example scenario in which a UE operating in MR-DC, in response to an SCG failure, retains previously received conditional configurations for conditional PSCell Addition or Change (CPAC).

[0022] Figure 3B It is similar to Figure 3A The example message passing graph for the scenario, but in which conditional configuration is provided by SN instead of MN;

[0023] Figure 3C This is a message passing diagram of an example scenario in which the UE retains the previously received conditional configuration for CPAC in response to SCG failure and applies the configuration if the candidate cell is suitable, regardless of whether the conditions are met.

[0024] Figure 3D It is similar to Figure 3A and Figure 3B The example scenario is shown in the message passing diagram, but in this scenario, the UE only notifies the MN of the SCG failure after failing to connect to the candidate cell within a predetermined time period;

[0025] Figure 3E It is similar to Figure 3A The example scenario's message passing diagram shows the SN providing conditional configuration for CPAC after the UE detects an SCG failure.

[0026] Figure 3F It is similar to Figure 3A and Figure 3B The example scenario is a message passing diagram, but in which the UE suspends conditional operation against CPAC in response to SCG failure until the RAN configures a new PSCell;

[0027] Figure 3G This is a message passing diagram of an example scenario in which a UE operating in MR-DC releases previously received conditional configurations for CPAC in response to an SCG failure, according to the technology of this disclosure.

[0028] Figure 4A This is a message passing diagram of an example scenario in which a UE operating in an MR-DC fails to connect to the C-PSCell and resumes communication with the SN on the PSCell, according to the technology disclosed herein.

[0029] Figure 4B It is similar to Figure 4A The example scenario is shown in the message passing diagram, but in which the UE fails to resume communication with the SN on the PSCell;

[0030] Figure 4C It is similar to Figure 4B The example scenario's message passing diagram shows the scenario, but the UE retains the C-SN configuration;

[0031] Figure 4D It is similar to Figure 4C The example scenario is shown in the message passing diagram, but in this scenario, the UE releases the C-SN configuration;

[0032] Figure 5A This is a message passing diagram of an example scenario in which a UE operating in MR-DC retains conditional configuration for a conditional SN add or change (CSAC) procedure in response to an SCG failure, according to the technology disclosed herein.

[0033] Figure 5B It is similar to Figure 5AThe example scenario is shown in the message passing diagram, but the UE only notifies the MN SCG of failure after failing to connect to the candidate cell within a predetermined time period;

[0034] Figure 5C It is similar to Figure 5A The example scenario's message passing diagram shows that MN provides conditional configuration for CSAC after the UE detects SCG failure.

[0035] Figure 5D It is similar to Figure 5A The example scenario is a message passing diagram, but in which the UE suspends conditional operation against CSAC in response to SCG failure until the RAN configures a new PSCell;

[0036] Figure 5E This is a message passing diagram of an example scenario in which a UE operating in MR-DC releases previously received conditional configurations for CSAC in response to an SCG failure, according to the technology of this disclosure.

[0037] Figure 6A This is a message passing diagram of an example scenario in which a UE operating in an MR-DC fails to connect to the C-PSCell and resumes communication with the SN on the PSCell, according to the technology disclosed herein.

[0038] Figure 6B It is similar to Figure 6A The example scenario is shown in the message passing diagram, but in which the UE fails to resume communication with the SN on the PSCell;

[0039] Figure 7 This is a flowchart of an example method for managing conditional configuration based on the type of SCG failure and conditional procedure, which can be implemented in the UE of this disclosure;

[0040] Figure 8 This is a flowchart of an example method for managing conditional configuration in light of SCG failures on candidate cells and the results of random access procedures, which can be implemented in the UE of this disclosure;

[0041] Figure 9 This is a flowchart of an example method for notifying the RAN of a communication failure with the SN by using additional information indicating that the UE has failed to connect to the C-PSCell when the UE is operating in the MR-DC, which can be implemented in the UE disclosed herein;

[0042] Figure 10 This is a flowchart of an example method for determining whether a UE should notify the RAN of a failure of a conditional procedure for a cell group, which can be implemented in a UE of this disclosure;

[0043] Figure 11 This is a flowchart of an example method for configuring conditional settings after an SCG failure is detected, which can be implemented in the UE of this disclosure;

[0044] Figure 12 This is a flowchart of an example method for managing condition configuration after an SCG failure is detected, which includes a suspension condition procedure and can be implemented in the UE of this disclosure;

[0045] Figure 13 This is a flowchart of an example method for managing conditional configurations after a failure to communicate with the SN is detected, which includes releasing the conditional configurations and can be implemented in the UE of this disclosure;

[0046] Figure 14 This is a flowchart of an example method for resuming communication after failing to connect to the C-PSCell, which can be implemented in the UE of this disclosure;

[0047] Figure 15 This is a flowchart of an example method for managing communication with the UE after an SCG failure is detected, which can be implemented in the RAN of this disclosure;

[0048] Figure 16 This is a flowchart of another example method for managing communication with the UE after an SCG failure is detected, which can be implemented in the RAN of this disclosure;

[0049] Figure 17 This is a flowchart of an example method for managing mobility that can be implemented in the UE of this disclosure;

[0050] Figure 18 This is a flowchart of an example method for configuring a UE that can be implemented in the RAN of this disclosure. Detailed Implementation

[0051] As discussed in detail below, for example, when a UE operating in a DC detects an SCG failure, the UE and / or one or more base stations manage conditional configurations for procedures such as conditional PSCell addition or change (CPAC) (also known as conditional PSCell change (CPC)). Before discussing the techniques that the UE or base station can implement to manage conditional configurations in these scenarios, refer to [reference needed]. Figures 1A-1C Consider example communication systems that utilize these technologies.

[0052] First refer to Figure 1AExample wireless communication system 100 includes UE 102, base station (BS) 104A, base station 106A, and core network (CN) 110. Base stations 104A and 106A can operate in RAN 105 connected to the same core network (CN) 110. For example, CN 110 can be implemented as an evolved packet core (EPC) 111 or a fifth-generation (5G) core (5GC) 160.

[0053] In addition to other components, EPC 111 may include a Serving Gateway (S-GW) 112 and a Mobility Management Entity (MME) 114. S-GW 112 is typically configured to transmit user plane packets related to audio calls, video calls, internet traffic, etc., and 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, UPF 162 is configured to transmit user plane packets related to audio calls, video calls, internet traffic, etc., AMF 164 is configured to manage authentication, registration, paging, and other related functions, and SMF 166 is configured to manage PDU sessions.

[0054] like Figure 1A As shown, base station 104A supports cell 124A, and base station 106A supports cell 126A. Cells 124A and 126A can partially overlap, allowing UE 102 to communicate in the DC with base stations 104A and 106A, which operate as the primary node (MN) and secondary node (SN), respectively. For direct message exchange during the DC scenario and other scenarios discussed below, MN 104A and SN 106A can support either the X2 or Xn interface. Typically, CN 110 can connect to any suitable number of base stations supporting NR cells and / or EUTRA cells. See below for reference. Figure 1B An example configuration in which the EPC 110 is connected to an additional base station is discussed.

[0055] Base station 104A is equipped with processing hardware 130, which may include one or more general-purpose processors (such as CPUs) and a non-transitory computer-readable memory storing machine-readable instructions executable on one or more general-purpose processors and / or dedicated processing units. In an example embodiment, processing hardware 130 includes a condition configuration controller 132 configured to manage condition configuration for one or more condition procedures (such as CHO, CPAC, or CSAC) when base station 104A operates as an MN.

[0056] Base station 106A is equipped with processing hardware 140, which may also include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions executable on one or more general-purpose processors and / or dedicated processing units. In an example embodiment, processing hardware 140 includes a condition configuration controller 142 configured to manage condition configuration for one or more condition procedures (such as CHO, CPAC, or CSAC) when base station 106A operates as an SN.

[0057] Still referencing Figure 1A UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors (such as CPUs) and a non-transitory computer-readable memory storing machine-readable instructions executable on one or more general-purpose processors and / or dedicated processing units. In an example embodiment, processing hardware 150 includes a UE condition configuration controller 152 configured to manage condition configuration for one or more condition procedures.

[0058] More specifically, condition configuration controllers 132, 142, and 152 may implement at least some of the techniques discussed with reference to the messaging and flowcharts below to receive condition configurations, release condition configurations in response to certain events, apply condition configurations, etc. Although Figure 1A While conditional configuration controllers 132 and 142 are illustrated as separate components, in at least some scenarios, base stations 104A and 106A may have similar implementations and operate as MN or SN nodes in different scenarios. In these implementations, each of base stations 104A and 106A may implement conditional configuration controllers 132 and 142 to support MN and SN functions, respectively.

[0059] In operation, UE 102 can use radio bearers (e.g., DRB or SRB) terminated at different times on MN 104A or SN 106A. When communicating on the radio bearers in the uplink (from UE 102 to BS) and / or downlink (from base station to UE 102) directions, UE 102 can apply one or more security keys. In some cases, the UE can use different RATs to communicate with base stations 104A and 106A. Although the examples below may specifically involve a particular RAT type (5G NR or EUTRA), in general, the techniques disclosed herein can also be applied to other suitable radio access and / or core network technologies.

[0060] Figure 1BAn example wireless communication system 100 in which communication devices can implement these technologies is depicted. The wireless communication system 100 includes a UE 102, base stations 104A, 104B, 106A, 106B, and a core network (CN) 110. The UE 102 is initially connected to base station 104A. Base stations 104B and 106B may have similar processing hardware to base station 106A. The UE 102 is initially connected to base station 104A.

[0061] In some scenarios, base station 104A can perform on-the-spot SN addition to configure UE 102 to operate in dual connectivity (DC) with base station 104A (via PCell) and with base station 106A (via PSCell, different from cell 126A). Base stations 104A and 106A operate as the MN and SN of UE 102, respectively. In some cases, UE 102 can operate in MR-DC connectivity mode, for example, communicating with base station 104A using 5G NR and with base station 106A using EUTRA, or communicating with base station 104A using EUTRA and with base station 106A using 5G NR.

[0062] At a certain moment, while UE 102 is communicating in a DC with MN 104A and S-SN 106A, MN 104A can perform an instant SN change to change UE 102's SN from base station 106A (source SN or "S-SN") to base station 104B (target SN or "T-SN"). In another scenario, SN 106A can perform an instant PSCell change to change UE 102's PSCell to cell 126A. In one implementation, SN 106A can send a configuration to UE 102 via a signaling radio bearer (SRB) (e.g., SRB3) to change the PSCell to cell 126A for instant PSCell change. In another implementation, SN 106A can send a configuration to UE 102 via MN 104A to change the PSCell to cell 126A for instant PSCell change. MN 104A can send an instant configuration to UE 102 via SRB1 to change PSCell to cell 126A.

[0063] In other scenarios, base station 104A can execute a conditional SN addition procedure to first configure base station 106B as the C-SN of UE 102, i.e., Conditional SN Addition or Change (CSAC). In this case, UE 102 can be in a single connectivity (SC) with base station 104A, or in a distribution center (DC) with both base stations 104A and 106A. If UE 102 is in a DC with both base stations 104A and 106A, MN 104A can determine to execute the conditional SN addition procedure in response to a request received from base station 106A, or in response to one or more measurements received from UE 102 or obtained by MN 104A from measurements of signals received from UE 102. Compared to the immediate SN addition case discussed above, UE 102 does not immediately attempt to connect to C-SN 106B. In this scenario, base station 104A again operates as MN, but base station 106B initially operates as a C-SN instead of an SN.

[0064] More specifically, when UE 102 receives the configuration for C-SN 106B, UE 102 does not connect to C-SN 106B until UE 102 has determined that a certain condition is met (in some cases, UE 102 may consider multiple conditions, but for convenience, the following discussion only involves a single condition). When UE 102 determines that the condition has been met, UE 102 connects to C-SN 106B, causing C-SN 106B to begin operating as SN 106B for UE 102. Therefore, although base station 106B operates as a C-SN rather than an SN, base station 106B is not yet connected to UE 102 and, correspondingly, is not yet serving UE 102. In some implementations, UE 102 can disconnect from SN 106A to connect to C-SN 106B.

[0065] In other scenarios, UE 102 is located at MN 104A (via PCell) and SN 106A (via PSCell different from cell 126A), and is not in Figure 1AIn the DC (shown in the diagram). SN 106A can perform a Conditional PSCell Add or Change (CPAC) to configure a candidate PSCell (C-PSCell) 126A for UE 102. If UE 102 is configured as a Signaling Radio Bearer (SRB) (e.g., SRB3) to exchange RRC messages with SN 106A, SN 106A can (e.g., in response to one or more measurement results that can be received from UE 102 via SRB or via MN 104A, or that can be obtained by SN 106A from measurements of signals received from UE 102) send the configuration for C-PSCell 126A to UE 102 via SRB. In the case of via MN 104A, MN 104A receives the configuration for C-PSCell 126A. Compared to the immediate PSCell change case discussed above, UE 102 does not immediately disconnect from the PSCell and attempts to connect to C-PSCell 126A.

[0066] More specifically, when UE 102 receives the configuration for C-PSCell 126A, UE 102 does not connect to C-PSCell 126A until UE 102 has determined that a certain condition is met (in some cases, UE 102 may consider multiple conditions, but for convenience, the following discussion only involves a single condition). When UE 102 determines that the condition has been met, UE 102 connects to C-PSCell 126A, causing C-PSCell 126A to begin operating as PSCell 126A for UE 102. Therefore, although cell 126A operates as C-PSCell instead of PSCell, SN 106A may not yet be connected to UE 102 via cell 126A. In some implementations, UE 102 can disconnect from PSCell to connect to C-PSCell 126A.

[0067] In some scenarios, the conditions associated with CSAC or CPAC may be that the signal strength / quality detected by UE 102 on C-PSCell 126A of SN 106A or on C-PSCell 126B of C-SN 106B 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 C-PSCell 126A are higher than a threshold configured by MN 104A or SN 106A or a predetermined or pre-configured threshold. When UE 102 determines that the signal strength / quality on C-PSCell 126A of SN 106A is sufficiently good (again, measured relative to one or more quantization thresholds or other quantization metrics), UE 102 may perform a random access procedure with SN 106A on C-PSCell 126A to connect to SN 106A. After UE 102 successfully completes the random access procedure on C-PSCell 126A, C-PSCell 126A becomes the PSCell 126A of UE 102. SN 106A can then begin transmitting data (user plane data or control plane data) with UE 102 via PSCell 126A. In another example, UE 102 determines that a condition is met when one or more measurements obtained by UE 102 on C-PSCell 126B are higher than a threshold configured by MN 104A or C-SN 106B, or higher than a predetermined or pre-configured threshold. When UE 102 determines that the signal strength / quality on C-PSCell 126B of C-SN 106B is sufficiently good (again, measured relative to one or more quantization thresholds or other quantization metrics), UE 102 can perform a random access procedure with C-SN 106B on C-PSCell 126B to connect to C-SN 106B. After UE 102 successfully completes the random access procedure on C-PSCell 126B, C-PSCell 126B becomes UE 102's PSCell 126B, and C-SN 106B becomes SN 106B. SN 106B can then begin transmitting data (user plane data or control plane data) with UE 102 via PSCell 126B.

[0068] In various configurations of the wireless communication system 100, base station 104A can be implemented as a primary eNB (MeNB) or primary gNB (MgNB), and base station 106A or 106B can be implemented as a secondary gNB (SgNB) or candidate SgNB (C-SgNB). UE 102 can communicate with base station 104A and base station 106A or 106B (106A / B) via the same RAT (such as EUTRA or NR) or different RATs. When base station 104A is a MeNB and base station 106A is an SgNB, UE 102 can be in an EUTRA-NR DC (EN-DC) with both a MeNB and an SgNB. In this scenario, MeNB 104A may or may not configure base station 106B as a C-SgNB for UE 102. In this scenario, SgNB 106A can configure cell 126A as a C-PSCell for UE 102. When base station 104A is a MeNB and base station 106A is the C-SgNB of UE 102, UE 102 can be in an SC with a MeNB. In this scenario, MeNB 104A may or may not configure base station 106B as another C-SgNB for UE 102.

[0069] In some cases, MeNB, SeNB, or C-SgNB is implemented as ng-eNB instead of eNB. When base station 104A 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 Mng-eNB and SgNB. In this scenario, MeNB 104A may or may not configure base station 106B as the C-SgNB for UE 102. In this scenario, SgNB 106A can configure cell 126A as the C-PSCell for UE 102. When base station 104A is the Mng-NB and base station 106A is the C-SgNB for UE 102, UE 102 can be in an SC with the Mng-NB. In this scenario, Mng-eNB 104A may or may not configure base station 106B as another C-SgNB for UE 102.

[0070] When base station 104A is a MgNB and base stations 106A / B are SgNBs, UE 102 can be in an NR-NR DC (NR-DC) with both MgNB and SgNB. In this scenario, MeNB 104A may or may not configure base station 106B as a C-SgNB for UE 102. In this scenario, SgNB 106A can configure cell 126A as a C-PSCell for UE 102. When base station 104A is a MgNB and base station 106A is a C-SgNB for UE 102, UE 102 can be in an SC with a MgNB. In this scenario, MgNB 104A may or may not configure base station 106B as another C-SgNB for UE 102.

[0071] When base station 104A 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 a MgNB and a Sng-eNB. In this scenario, MgNB 104A may or may not configure base station 106B as a C-Sng-eNB for UE 102. In this scenario, Sng-eNB 106A may configure cell 126A as a C-PSCell for UE 102. When base station 104A 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 a MgNB. In this scenario, MgNB 104A may or may not configure base station 106B as another C-Sng-eNB for UE 102.

[0072] Base stations 104A, 106A, and 106B can connect to the same core network (CN) 110, which can be either an Evolved Packet Core (EPC) 111 or a Fifth Generation Core (5GC) 160. Base station 104A 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. In order to exchange messages directly during the scenarios discussed below, base stations 104A, 106A and 106B can support the X2 or Xn interface.

[0073] like Figure 1B As shown, base station 104A supports cell 124A, base station 104B supports cell 124B, base station 106A supports cell 126A, and base station 106B supports cell 126B. Cells 124A and 126A can partially overlap, as can cells 124A and 124B, allowing UE 102 to communicate with base station 104A (operating as MN) and base station 106A (operating as SN) in the DC, and to communicate with base station 104A (operating as MN) and SN 104B when an SN change is completed. More specifically, when UE 102 operates in a DC with base stations 104A and 106A, base station 104A operates as a MeNB, Mng-eNB, or MgNB, and base station 106A operates as an SgNB or Sng-eNB. Cells 124A and 126B can partially overlap. When UE 102 is in an SC with base station 104A, base station 104A operates as a MeNB, Mng-eNB, or MgNB, and base station 106B operates as a C-SgNB or C-Sng-eNB. When UE 102 operates in a DC with base stations 104A and 106A, base station 104A operates as a MeNB, Mng-eNB, or MgNB, base station 106A operates as an SgNB or Sng-eNB, and base station 106B operates as a C-SgNB or C-Sng-eNB.

[0074] 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 relate 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+.

[0075] Figure 1CAn example distributed implementation of a base station, such as base station 104A, 104B, 106A, or 106B, is depicted. The base station in this implementation may include a centralized unit (CU) 172 and one or more distributed units (DUs) 174. CU 172 is equipped with processing hardware, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions executable on 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 that 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 one or more general-purpose processors and / or dedicated processing units. In some examples, the processing hardware in example embodiments includes a Media Access Control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., random access procedures), and a Radio Link Control (RLC) controller configured to manage or control one or more RLC operations or procedures when base station 106A operates as an MN, SN, or candidate SN (C-SN). The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0076] Figure 2A simplified illustration shows an example radio protocol stack 200 that UE 102 can use to communicate with an eNB / ng-eNB or gNB (e.g., one or more of base stations 104A, 104B, 106A, 106B). In the example stack 200, the EUTRA physical layer (PHY) 202A provides a transport channel to the EUTRA MAC sublayer 204A, which in turn provides a logical channel to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A then provides an RLC channel to the EUTRA PDCP sublayer 208, and in some cases, a channel to the NR PDCP sublayer 210. Similarly, the NR PHY 202B provides a transport channel to the NR MAC sublayer 204B, which in turn provides a logical channel to the NR RLC sublayer 206B. The NR RLC sublayer 206B then provides an RLC channel to the NR PDCP sublayer 210. In some implementations, UE 102 supports, for example Figure 2 The EUTRA and NR stacks shown are designed to support handover between EUTRA and NR base stations and / or support DC on the EUTRA and NR interfaces. Additionally, as... Figure 2 As shown, UE 102 can support the layering of NR PDCP sublayer 210 above EUTRA RLC sublayer 206A.

[0077] EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 receive packets that can be referred to as Service Data Units (SDUs) (e.g., from Internet Protocol (IP) layers directly or indirectly layered above 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). Except where the difference between SDU and PDU is relevant, for simplicity, this disclosure refers to both SDU and PDU as "packets".

[0078] For example, on the control plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide SRBs to exchange RRC messages. On the user plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide DRBs to support data exchange.

[0079] In a scenario where UE 102 operates in an EUTRA / NR DC (EN-DC) with base station 104A operating as a MeNB and base station 106A operating as an SgNB, wireless communication system 100 can provide UE 102 with an MN-terminated bearer using EUTRA PDCP sublayer 208 or an MN-terminated bearer using NR PDCP sublayer 210. In various scenarios, wireless communication system 100 can also provide UE 102 with an SN-terminated bearer using only NR PDCP sublayer 210. The MN-terminated bearer can be an MCG bearer, an SCG bearer, or a separate bearer. The SN-terminated bearer can be an MCG bearer, an SCG bearer, or a separate bearer. The MN-terminated bearer can be an SRB (e.g., SRB1 or SRB2) or a DRB.

[0080] Next, refer to Figures 3A-6B Let's discuss a few example scenarios in which UE and / or base station management use conditional configuration for conditional procedures.

[0081] First refer to Figure 3A In scenario 300A, base station 104A operates as the MN, and base station 106A operates as the SN. Initially, UE 102 is in an MR-DC with MN 104A and SN 106A. Depending on the specific SN configuration, UE 102 transmits UL PDUs and / or DL ​​PDUs via PSCell to SN 106A. Then, SN 106A determines 304 that it should generate a C-SN configuration for Conditional PSCell Addition or Modification (CPAC). For example, SN 106A may make this determination based on one or more measurements received from UE 102 via MN 104A, directly from the UE (e.g., via a signaling radio bearer (SRB) established between UE 102 and SN 106A, or via a physical control channel), or obtained by SN 106A from measurements of signals, control channels, or data channels received from UE 102. More intelligently, SN 106A can deduce or estimate that UE 102 is moving toward the coverage of cell 126A based on uplink signals received from UE 102 or multiple positioning measurement results received from UE 102. In response to this determination, SN 106A generates a 304 C-SN configuration.

[0082] In example scenario 300A, MN 104A then sends 306 C-SN configuration to MN 104A. MN 104A then sends 308 C-SN configuration to UE 102. In some implementations, SN 106A generates a conditional configuration including the C-SN configuration at event 304, and generates an RRC reconfiguration message including the conditional configuration. MN 104A then sends 306 RRC reconfiguration message to MN 104A. MN 104A then sends 308 RRC reconfiguration message including the conditional configuration to UE 102. In other implementations, MN 104A generates a conditional configuration including the C-SN configuration, and generates an RRC reconfiguration message including the conditional configuration. MN 104A sends 308 RRC reconfiguration message including the conditional configuration to UE 102.

[0083] In some implementations, UE 102 sends a 310RRC reconfiguration complete message to MN 104A in response to the aforementioned RRC reconfiguration message. MN 104A may send a 312SN message (e.g., an SN reconfiguration complete message) to SN 106A in response to the RRC reconfiguration complete message. Events 304-312 may collectively define CPAC configuration procedure 320A.

[0084] In one implementation, to send an RRC reconfiguration message, MN 104A sends an RRC container message including the RRC reconfiguration to UE 102. In response, in one implementation, UE 102 sends an RRC container response message including an RRC reconfiguration completion message to MN 104A, thus sending a 310 RRC reconfiguration completion message. MN 104A may send a 312SN message to SN 106A in response to the RRC container response message. Furthermore, MN 104A may include the RRC reconfiguration completion message in the 312 SN message sent by MN 104A. In another implementation, UE 102 does not generate an RRC container response message to encapsulate the UE-sent 310 RRC reconfiguration completion message.

[0085] When SN 106A is implemented as an ng-eNB, the RRC reconfiguration message generated by SN 106A is an RRCConnectionReconfiguration message, and the RRC reconfiguration completion message received by MN 104A from 310 is an RRCConnectionReconfigurationComplete message. When SN 106A is implemented as a gNB, the RRC reconfiguration message generated by SN 106A is an RRCReconfiguration message, and the RRC reconfiguration completion message received by MN 104A from 310 is an RRCReconfigurationComplete message. When MN 104A is implemented as an eNB or ng-eNB, the RRC container message is an RRCConnectionReconfiguration message, and the RRC container response message is an RRCConnectionReconfigurationComplete message. When MN 104A is implemented as a gNB, the RRC container message is an RRCReconfiguration message, and the RRC container response message is an RRCReconfigurationComplete message.

[0086] When the MN 104A is implemented as an eNB or ng-eNB, the RRC reconfiguration message generated by the MN 104A is an RRCConnectionReconfiguration message, and the RRC reconfiguration completion message is an RRCConnectionReconfigurationComplete message. When the MN 104A is implemented as a gNB, the RRC reconfiguration message generated by the MN 104A is an RRCReconfiguration message, and the RRC reconfiguration completion message is an RRCReconfigurationComplete message.

[0087] Later, UE 102 detects a 322SCG failure and, in response, retains the C-SN configuration for CPAC. UE 102 sends a 324SCG failure information message to MN 104A to notify MN 104A of the SCG failure. In response to receiving the 324SCG failure information message, MN 104A can send an SN message to SN 106A, causing SN 106A to suspend communication with UE 102 via SN radio resources (i.e., SCG radio resources on SN 106A's PSCell and (if configured) SCells). In response to receiving a 326SN message, or more generally, in response to determining that UE 102 has disconnected from SN 106A, SN 106A can suspend 328 communication with the UE via SN radio resources. Therefore, SN 106A does not expend its radio resources to attempt to send data to UE 102, which has already detected an SCG failure. After SN 106A suspends communication with UE 102 via SN radio resources, for example, if SN 106A receives data packets from CN 110 (e.g., S-GW 112 or UPF 162) or an edge server, SN 106A may send 330 data PDUs (e.g., PDCP PDUs) including data packets to MN 104A. MN 104A then sends 332 data PDUs to UE 102. Therefore, SN 106A sends 330 data PDUs to UE 102 via MN 104A. The data PDUs may be associated with an SN-termination bearer, which may be a decoupled bearer or an MCG bearer.

[0088] Generally, SCG failure may be related to the SCG radio resources used by UE 102 to communicate with SN 106A. SCG failure can be, for example, a radio link failure, an SCG change failure (or an SCG synchronization reconfiguration failure), an SCG reconfiguration failure, or an SRB3 integrity failure. UE 102 can detect an SCG failure when it detects a random access problem on the PSCell, or when timers T310 or T313 used to monitor the radio link on the PSCell expire, or when the maximum number of retransmissions with SN 106A on the SCG radio resources at the RLC layer has been reached. Furthermore, an SCG change failure can correspond to an immediate SCG change failure (or an immediate SCG synchronization reconfiguration failure) or a conditional SCG change failure (or a conditional SCG synchronization reconfiguration failure). The term "SCG change" can be applied to either a PSCell change or an SN change. An immediate SCG synchronization reconfiguration failure occurs when UE 102 fails in an RRC reconfiguration procedure involving a synchronized reconfiguration for an immediate SCG change. Conditional SCG changes can correspond to CPAC or CSAC. Conditional SCG synchronization reconfiguration failure occurs when UE 102 fails during the RRC reconfiguration procedure involving synchronized reconfiguration for conditional SCG changes. This failure occurs if UE 102 detects that the condition is met or the C-PSCell is appropriate (for...). Figure 3C If UE 102 fails to connect to the C-PSCell (i.e., UE 102 fails in CPAC or CSAC) despite being described as "suitable," then UE 102 detects a 322 conditional SCG change failure (or conditional SCG synchronization reconfiguration failure). SCG reconfiguration failures can include both immediate and conditional SCG reconfiguration failures. If UE 102 receives an RRC reconfiguration message on an SRB (e.g., SRB3) established between UE 102 and SN 106A, and determines that the RRC reconfiguration message contains an invalid configuration not in the conditional configuration (or C-SN configuration), then UE 102 detects an immediate SCG reconfiguration failure. If UE 102 receives a C-SN configuration and identifies that the C-SN configuration is invalid (e.g., the C-SN configuration contains an invalid configuration), then UE 102 detects a conditional SCG reconfiguration failure.

[0089] Based on the above, SCG failures can be classified into 8 types (or causes): (1) random access problem, (2) timer T310 or T313 expires, (3) exceeding the maximum number of retransmissions at the RLC layer, (4) instant SCG change failure (or instant SCG synchronization reconfiguration failure), (5) conditional SCG change failure (or conditional SCG synchronization reconfiguration failure), (6) instant SCG reconfiguration failure, (7) conditional SCG reconfiguration failure, or (8) SRB3 integrity failure.

[0090] In other implementations, some of the SCG failure types listed above can be combined into a single failure type. For example, immediate SCG reconfiguration failure and conditional SCG reconfiguration failure can be combined into SCG reconfiguration failure. In another example, immediate SCG change failure and conditional SCG change failure can be combined into SCG reconfiguration failure.

[0091] In some implementations, if SCG failure is the first failure type, UE 102 retains the C-SN configuration, and if SCG failure is the second failure type, UE 102 releases the C-SN configuration. For example, the second failure type could be a conditional SCG change failure or a conditional SCG reconfiguration failure, and the first failure type could be a different failure type.

[0092] In some implementations, the SN message at event 326 may be an SN modification request message, and in response, SN 106A may send an SN modification request response message to MN 104A. In other implementations, the SN message may be an SN release request message, and in response, SN 106A may send an SN release request response message to MN 104A. In some implementations, if SN 106A does not receive a signal from UE 102 on the uplink channel, SN 106A determines that SN 106A has disconnected from UE 102. These signals may include PDUs or control signals, such as Hybrid Automatic Repeat Request (HARQ) acknowledgments, HARQ negative acknowledgments, Uplink Control Information (UCI) Channel State Information (CSI), or Sound Reference Signals (SRS). The uplink channel may be a Physical Uplink Control Channel (PUCCH), a Physical Uplink Shared Channel (PUSCH), or an Uplink Shared Channel (UL-SCH).

[0093] Optionally, after detecting a 322SCG failure and retaining the 322C-SN configuration, UE 102 may detect that 334 meets the conditions for connecting to C-PSCell 126A, and initiate a random access procedure on C-PSCell 126A in response to this detection. For convenience, this discussion may refer to conditions or configurations in singular form, but it will be understood that multiple conditions may exist, and condition configurations may include one or more configuration parameters to specify one or more conditions. UE 102 then (e.g., using one or more random access configurations in the C-SN configuration) performs the random access procedure with SN106A via C-PSCell 126A. During or after the random access configuration for connecting to C-PSCell 126A, UE 102 may send a 338RRC reconfiguration complete message via C-PSCell 126A (e.g., on SRB3). Alternatively, UE 102 can send a 338RRC reconfiguration complete message to SN 106A via MN 104A. In this case, UE 102 can send a 338RRC container message (e.g., a ULInformationTransferMRDC message or a newly defined RRC message) including the RRC reconfiguration complete message to MN 104A (e.g., on SRB1), and MN 104A then sends the RRC reconfiguration message to SN 106A in an SN message (e.g., an RRC transfer message, an SN reconfiguration complete message, or a newly defined SN message). The newly defined RRC message can be specifically designed for UE 102 to send the RRC reconfiguration complete message in response to connecting to C-PSCell 126A. If MN 104A receives the newly defined RRC message, MN 104A can forward the RRC reconfiguration complete message to SN 106A. The newly defined SN message can be specifically designed for MN 104A to send the RRC reconfiguration complete message to SN 106A. If SN 106A receives an RRC reconfiguration message via the newly defined SN message, SN 106A can determine that UE 102 is connected to C-PSCell 126A. Alternatively, UE 102 does not send a 338RRC reconfiguration message to SN 106A. If SN 106A identifies UE 102 in the random access procedure, SN 106A resumes communication with UE 102 via SN radio resource 340. If UE 102 successfully completes the random access procedure, UE 102 communicates with SN 106A via C-PSCell 126A according to the configuration in the C-SN configuration 342.

[0094] In some implementations, the random access procedure may be a four-step random access procedure or a two-step random access procedure. In other implementations, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. In some implementations, UE 102 includes an RRC reconfiguration completion message in message 3 of the four-step random access procedure or in message A of the two-step random access procedure.

[0095] In some implementations, SN 106A includes a trigger condition configuration that configures UE 102 to detect condition 334 in a condition configuration generated by SN 106A. SN 106A may include a configuration ID identifying the condition configuration or the C-SN configuration within the condition configuration. In other implementations, SN 106A may send the trigger condition configuration at event 306, and MN 104A may further include the trigger condition configuration in a condition configuration generated by MN 104A. For simplicity in the following description, CPAC configuration is used to represent the C-SN configuration and the trigger condition configuration, condition configuration, or RRC reconfiguration message generated by SN 106A as described above.

[0096] Continue to refer to Figure 3A In some implementations, the C-SN configuration can be a complete and self-contained configuration (i.e., a full configuration). The C-SN configuration may include a full configuration indication (information element (IE) or field) that identifies the C-SN configuration as a full configuration. In this case, UE 102 can communicate with SN 106A using the C-SN configuration without relying on the SN configuration. On the other hand, in other cases, the C-SN configuration may include an "incremental" configuration, or one or more configurations that extend a previously received SN configuration. In these cases, UE 102 can communicate with SN 106A using both the incremental C-SN configuration and the SN configuration.

[0097] C-SN configuration may include multiple configuration parameters applied by UE 102 when communicating with SN 106A via C-PSCell 126A. These parameters can configure C-PSCell 126A and zero or more candidate secondary cells (C-SCells) of SN 106A to UE 102. They can also configure the radio resources used by UE 102 for communicating with SN 106A via C-PSCell 126A and zero or more C-SCells. Finally, they can configure zero or more radio bearers. These radio bearers may include SRBs and / or one or more DRBs.

[0098] The SN configuration may include multiple configuration parameters for UE 102 to communicate with SN 106A via SN 106A's PSCell and zero or more secondary cells (SCells). These configuration parameters can configure the radio resources used by UE 102 to communicate with SN 106A via SN 106A's PSCell and zero or more SCells. Multiple configuration parameters can also configure zero or more radio bearers. One or more radio bearers may include SRBs and / or one or more DRBs.

[0099] In some implementations, SN 106A may include CPAC configuration in an SN modification response message received from MN 104A in response to an SN modification request message, and send the SN modification request response message to MN 104A during event 306. In other implementations, SN 106A may include CPAC configuration in an SN Modification Required message, and send a SN Modification Required message to MN 104A during event 306. SN 106A may indicate that the SN Modification Required response message or the SN Modification Required message is for CPAC, such that MN 104A can determine that the SN Modification Required response message or the SN Modification Required message includes conditional configuration for CPAC. In other implementations, SN 106A does not indicate CPAC in the SN Modification Required response message or the SN Modification Required message. In these implementations, the CPAC configuration from SN 106A is transparent to MN 104A, so MN 104A simply tunnels the CPAC configuration to UE 102 without processing the CPAC configuration.

[0100] In some implementations, the C-SN configuration may include a C-PSCell 126A configuring SN 106A and a group configuration (CellGroupConfig) IE for zero or one or more C-SCells. In one implementation, the C-SN configuration includes a radio bearer configuration. In another implementation, the C-SN configuration does not include a radio bearer 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. In various implementations, the C-SN configuration may be an RRCReconfiguration message conforming to 3GPP TS 38.331, an RRCReconfiguration-IE, or a CellGroupConfig IE. A complete configuration indication may be a field or IE conforming to 3GPP TS 38.331. In other implementations, C-SN configuration may include a C-PSCell 126A configuring SN 106A and an SCG-ConfigPartSCG-r12 IE for zero or one or more C-SCells. In some implementations, C-SN configuration is an RRCConnectionReconfiguration message, RRCConnectionReconfiguration-IE, or ConfigPartSCG-r12 IE conforming to 3GPP TS 36.331. A complete configuration indication may be a field or IE conforming to 3GPP TS 36.331.

[0101] In some implementations, the SN configuration may include a CellGroupConfig IE for configuring the PSCell, and may configure zero or one or more SCells of SN 106A. In one implementation, the SN configuration may be an RRCReconfiguration message, RRCReconfiguration-IE, or CellGroupConfig IE conforming to 3GPP TS 38.331. In other implementations, the SN configuration may include an SCG-ConfigPartSCG-r12 IE for configuring the PSCell, and may configure zero or one or more SCells of SN 106A. In one implementation, the SN configuration may be an RRCConnectionReconfiguration message, RRCConnectionReconfiguration-IE, or ConfigPartSCG-r12 IE conforming to 3GPP TS 36.331.

[0102] In some cases, UE 102 may receive one or more conditions in the trigger condition configuration during event 308 (discussed in the singular form here for convenience). UE 102 may use one or more conditions to determine whether to connect to C-PSCell 126A. If UE 102 detects that condition 334 is met, then UE 102 connects to C-PSCell 126A. That is, the condition (or “trigger condition”) triggers UE 102 to connect to C-PSCell 126A or perform C-SN configuration. However, if UE 102 does not detect that the condition is met, then UE 102 does not connect to C-PSCell 126A.

[0103] Still referencing Figure 3A In some cases, SN 106A may include CU 172 and one or more DU 174, such as Figure 1CAs shown. The UE communicates with the SN via the first DU 174 operating the PSCell 302. The second DU 174 operating the C-PSCell 126A can generate a C-SN configuration or a portion of a C-SN configuration and send the C-SN configuration or a portion of a C-SN configuration to the CU 172. If the second DU 174 generates a portion of the C-SN configuration, the CU 172 can generate the remainder of the C-SN configuration. When the CU 172 suspends communication with the UE via the SN radio resources 328, the CU 172 can send a UE context modification request message to cause the first DU 174 to suspend the lower layers and suspend communication with the UE 102. The first DU 174 can also send a UE context modification response message to the CU 172. The UE 102 executes the random access procedure 336 with the second DU 174, and the second DU 174 can identify the UE 102 in the random access procedure. The second DU 174 may receive a 338RRC reconfiguration complete message from UE 102 during or after the random access procedure. Furthermore, the second DU 174 may include the RRC reconfiguration complete message in an F1 Application Protocol (F1AP) message (e.g., a UL RRC message delivery message) and send an F1AP message to CU 172. CU 172 resumes communication with the UE via the second DU 174 in response to the F1AP message or the RRC reconfiguration complete message 338. CU 172 may also send a UE context release command message to the first DU 174 in response to the F1AP message or the RRC reconfiguration complete message 338, commanding the first DU 174 to release the UE context of UE 102. Alternatively, CU 172 resumes communication with the UE via the second DU 174 in response to recognition during the random access procedure. If the second DU 174 identifies UE 102 during the random access procedure, the second DU 174 may send another F1AP message to CU 172 including an indication of the identification. CU 172 may send a UE context release command message to the first DU 172, instructing the first DU 172 to release the UE context of UE 102 in response to the identification. In response to the UE context release command message, the first DU 172 releases the UE context of UE 102 and sends a UE context release complete message. The first DU and the second DU 174 may be the same DU operating PSCell and C-PSCell 126A, or they may be different DUs.

[0104] Now for reference Figure 3BScenario 300B involves CPAC without SN change, i.e., a conditional change of the SN's PSCell when the UE is already in a DC with both MN and SN. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figure 3A and Figure 3B The differences between the scenarios.

[0105] CPAC Configuration Program 320B is typically similar to Figure 3A The CPAC configuration procedure is 320A. However, in scenario 300B, SN106A directly sends a 307 RRC reconfiguration message including conditional configuration to UE 102, instead of... Figure 3A In scenario 300A, SN 106A sends an RRC reconfiguration message to UE 102 via MN 104A, as SN 106A does. In some implementations, SN 106A configures a first SRB to UE 102 via MN 104A and sends an RRC reconfiguration message to UE 102 via the first SRB. For example, SN 106A sends an SRB configuration message to MN 104A to configure the first SRB (e.g., SRB3), and MN 104A sends an SRB configuration message to UE via a second SRB (e.g., SRB1) between MN 104A and UE 102. In some implementations, UE 102 may send a 309 RRC reconfiguration complete message to SN 106A via the first SRB in response to the RRC reconfiguration message, instead of sending a 310 RRC reconfiguration complete message to MN 104A as in scenario 300A. In some implementations, UE102 may send a 338RRC reconfiguration message to SN 106A via the first SRB.

[0106] When SN 106A is implemented as an ng-eNB, the RRC reconfiguration message 307 sent by SN 106A is an RRCConnectionReconfiguration message, and the RRC reconfiguration completion message 309 received by SN 106A is an RRCConnectionReconfigurationComplete message. When SN 106A is a gNB, the RRC reconfiguration message 307 sent by SN 106A is an RRCReconfiguration message, and the RRC reconfiguration completion message 309 received by SN 106A is an RRCReconfigurationComplete message.

[0107] Now for reference Figure 3CScenario 300C involves CPAC without SN change, i.e., a conditional change of the SN's PSCell when the UE is already in a DC with both MN and SN. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figure 3A and Figure 3C The differences between the scenarios.

[0108] Scene 300C is usually similar to Figures 3A-3B The scenarios 300A and 300B are depicted. However, in scenario 300C, UE 102 initiates a 335 random access procedure on the C-PSCell in response to detecting that the 335C-PSCell is suitable, regardless of whether UE 102 detects that the conditions for connecting to the C-PSCell are met. The “suitable” conditions can be pre-configured in UE 102 instead of being received from SN 106A at CPAC configuration procedures 320A or 320B. For example, the “suitable” conditions can be predefined in 3GPP specifications (e.g., 36.304 or 38.304). In some implementations, if UE 102 fails in a random access procedure triggered by UE 102 detecting that the C-PSCell is suitable, UE 102 releases the C-SN configuration. In other implementations, if UE 102 fails in a random access procedure triggered by UE 102 detecting that the C-PSCell is suitable, UE 102 retains the C-SN configuration.

[0109] Now for reference Figure 3D Scenario 300D involves CPAC without SN change, i.e., a conditional change of the SN's PSCell when the UE is already in a DC with both MN and SN. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figures 3A-3B and Figure 3D The differences between the scenarios.

[0110] After detecting the 322SCG failure, UE 102 initially did not seem to... Figures 3A-3BInstead of sending an SCG failure information message to the MN as in the previous method, the UE only notifies the MN of the SCG failure after failing to connect to the C-PSCell within a predetermined time period. Specifically, the UE 102 starts a 352 SCG failure recovery timer in response to an SCG failure (e.g., upon detecting an SCG failure). Before the SCG failure timer expires, the UE 102 detects that 354 conditions for connecting to the C-PSCell 126A are met or that the C-PSCell 126A is suitable, and initiates a random access procedure on the C-PSCell 126A in response to this detection. The UE 102 then (e.g., using one or more random access configurations in the C-SN configuration) performs a 336 random access procedure with SN 106A via the C-PSCell 126A. During or after the random access configuration, the UE 102 may send a 338 RRC reconfiguration complete message to connect to the C-PSCell 126A. If UE 102 successfully completes the random access procedure, UE 102 stops the 360SCG failure recovery timer and communicates with SN 106A via C-PSCell 126A according to the configuration in the C-SN configuration 342. If SN 106A recognizes UE 102 in the random access procedure, and SN 106A has suspended communication with UE 102 in response to detecting a disconnection from UE 102, SN 106A can resume communication with UE 102 via SN radio resources, such as... Figure 3A As described above. If UE 102 does not detect the conditions for connecting to the C-PSCell or that the C-PSCell is suitable before the 364SCG failure recovery timer expires, events 324-332, 334, or 335 and 336-342 may occur. In this way, UE 102 will not send a 324SCG failure information message in response to the detection of an SCG failure unless UE 102 does not detect the conditions for connecting to the C-PSCell or that the C-PSCell is suitable before the timer expires.

[0111] 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 MN and SN. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figure 3A and Figure 3E The differences between the scenarios.

[0112] exist Figure 3AIn this case, the CPAC configuration procedure 320A occurs before UE 102 detects an SCG failure. In contrast, in Figure 3E In this implementation, the CPAC configuration procedure 320A occurs after UE 102 detects a 323SCG failure. Upon receiving a 326SN message or detecting that UE 102 has disconnected from SN 106A, SN 106A sends CPAC configuration to UE 102 via CPAC configuration procedure 320A. In some implementations, UE 102 may include at least one measurement result in the SCG failure information message, and MN 104A may then send at least one measurement result to SN 106A in SN message 326. In other implementations, after UE 102 detects an SCG failure, UE 102 may send at least one measurement report message including at least one measurement result to SN 106A via MN 104A. SN 106A may determine whether to send CPAC configuration to UE 102 based on at least one measurement result via CPAC configuration procedure 320A. For example, if at least one measurement result is higher than a first threshold, SN 106A may send CPAC configuration to UE 102 via CPAC configuration procedure 320A.

[0113] In another example, if at least one measurement associated with the second PSCell is higher than a second threshold greater than a first threshold, SN 106A can execute an SN modification procedure with MN 104A to configure UE 102 to perform an immediate PSCell change to the second PSCell (e.g., the PSCell at event 302 or a new PSCell). In the SN modification procedure, SN 106A sends a request SN modification message to MN 104A, and MN 104A can respond with an SN modification confirmation message. MN 104A can send an SN modification request message to SN 106A in response to the request SN modification message, and in response, SN 106A can send an SN modification request response message. SN 106A configures UE 102 to perform an immediate PSCell change to the second PSCell in the RRC reconfiguration message within the request SN modification message or the SN modification request response message. Furthermore, MN 104A sends an RRC reconfiguration message to UE 102. UE 102 sends an RRC reconfiguration complete message to MN 104A in response to the RRC reconfiguration message, and MN 104A can then send an SN message including the RRC reconfiguration complete message to SN 106A. The SN message can be an SN modification confirmation message or an SN reconfiguration complete message. In some implementations, MN 104A includes the RRC reconfiguration message in an RRC container message and sends the RRC container message to UE 102. UE 102 can include the RRC reconfiguration complete message in an RRC container response message and send an RRC container response message to MN 104A in response to the RRC container message. Then, MN 104A sends an SN message including the RRC reconfiguration complete message (e.g., an SN modification confirmation message or an SN reconfiguration complete message) to SN 106A.

[0114] UE 102 immediately performs a random access procedure on the second PSCell in response to the RRC reconfiguration message. If SN 106A recognizes UE 102 during the random access procedure on the second PSCell, SN 106A can resume communication with the UE via SN radio resources. If UE 102 successfully completes the random access procedure, the UE operates in the DC with MN and SN and communicates with SN 106A via the second PSCell.

[0115] When SN 106A is implemented as an ng-eNB, the RRC reconfiguration message generated by SN 106A is an RRCConnectionReconfiguration message, and the RRC reconfiguration completion message received by MN 104A is an RRCConnectionReconfigurationComplete message. When SN 106A is implemented as a gNB, the RRC reconfiguration message generated by SN 106A is an RRCReconfiguration message, and the RRC reconfiguration completion message is an RRCReconfigurationComplete message. When MN 104A is implemented as an eNB or ng-eNB, the RRC container message is an RRCConnectionReconfiguration message, and the RRC container response message is an RRCConnectionReconfigurationComplete message. When MN 104A is implemented as a gNB, the RRC container message is an RRCReconfiguration message, and the RRC container response message is an RRCReconfigurationComplete message.

[0116] In another example, if at least one measurement result is below a first threshold or a third threshold smaller than the first threshold, SN 106A can execute an SN release procedure with MN 104A to configure UE 102 to release the MR-DC. In the SN release procedure, SN 106A sends a request SN release message to MN 104A, and MN 104A can respond with an SN release confirmation message. MN 104A configures UE 102 to release the MR-DC in an RRC reconfiguration message generated by MN 104A. In response to the RRC reconfiguration message, UE 102 immediately releases the MR-DC and sends an RRC reconfiguration complete message to MN 106A. At the time of MR-DC release, UE 102 is in an SC with MN 104A. When the MN 104A is implemented as an eNB or ng-eNB, the RRC reconfiguration message generated by the MN 104A is an RRCConnectionReconfiguration message, and the RRC reconfiguration completion message is an RRCConnectionReconfigurationComplete message. When the MN 104A is implemented as a gNB, the RRC reconfiguration message generated by the MN 104A is an RRCReconfiguration message, and the RRC reconfiguration completion message is an RRCReconfigurationComplete message.

[0117] Now for reference Figure 3F Scenario 300F involves the configuration of handling conditions when a UE operating in a DC with an MN and an SN detects an SCG failure. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figures 3A-3B and Figure 3F The differences between the scenarios.

[0118] Similar to scenarios 300A and 300B, UE 102 detects a 321SCG failure and retains the C-SN configuration for CPAC. However, in scenario 300F, UE 102 suspends 321CPAC operation in response to the SCG failure. After UE 102 suspends 321CPAC operation, UE 102 can stop detecting conditions for connecting to C-PSCell 126A, or stop connecting to C-PSCell 126A if UE 102 detects that the conditions for connecting to C-PSCell 126A are met.

[0119] In some implementations, UE 102 may include at least one measurement result in the SCG failure information message 324, and MN 104A may then send at least one measurement result to SN 106A in the SN message 326. In other implementations, after UE 102 detects an SCG failure, UE 102 may send at least one measurement report message including at least one measurement result to SN 106A via MN 104A. In other implementations, after UE 102 detects an SCG failure, UE 102 may send at least one measurement report message including at least one measurement result to MN 104A.

[0120] If at least one measurement associated with the second PSCell exceeds a threshold, SN 106A can initiate and execute an SN modification procedure with MN 104A to configure UE 102 to perform an immediate PSCell change to the second PSCell (e.g., the first PSCell at event 302 or a new PSCell). In the SN modification procedure, SN 106A sends a request for SN modification message to MN 104A, and MN 104A can respond with an SN modification confirmation message. MN 104A can send an SN modification request message to SN 106A in response to the request for SN modification message, and in response, SN 106A can send an SN modification request response message.

[0121] Alternatively, if at least one measurement associated with the second PSCell is above a threshold, MN 104A can initiate and execute an SN modification procedure with SN 106A to configure UE 102 to perform an immediate PSCell change to the second PSCell (e.g., the first PSCell at event 302 or a new PSCell). In the SN modification procedure, MN 104A can send an SN modification request message to SN 106A, and in response, SN 106A can send an SN modification request response message. The SN message can be an SN modification request message.

[0122] In an RRC reconfiguration message (e.g., a request for SN modification message or an SN modification request response message), SN 106A configures UE 102 to perform an immediate PSCell change to the second PSCell. Then, MN 104A sends a 372 RRC reconfiguration message to UE 102. If SN 106A does not configure UE 102 to release the C-SN configuration in the RRC reconfiguration message, UE 102 resumes 374 CPAC operation in response to the RRC reconfiguration message. After UE 102 resumes CPAC operation, UE 102 can begin detecting conditions for connecting to C-PSCell 126A, or connect to C-PSCell 126A if UE 102 detects that the conditions for connecting to C-PSCell 126A are met. If UE 102 detects conditions for connecting to C-PSCell 126A before completing random access procedure 380, UE 102 can connect to C-PSCell 126A after completing the random access procedure. Alternatively, UE 102 can resume CPAC operation 374 after completing random access procedure 380.

[0123] If SN 106A configures UE 102 to release C-SN configuration in the RRC reconfiguration message, then UE 102 releases 374 C-SN configuration in response to the RRC reconfiguration message.

[0124] UE 102 sends an RRC reconfiguration complete message (376) to MN 104A in response to the RRC reconfiguration message, and MN 104A can then send an SN message (378) including the RRC reconfiguration complete message to SN 106A. The SN message (378) received by SN 106A can be an SN modification confirmation message or an SN reconfiguration complete message. In some implementations, MN 104A can include the RRC reconfiguration message in an RRC container message and send the RRC container message to UE 102. UE 102 can include the RRC reconfiguration complete message in an RRC container response message and send an RRC container response message to MN 104A in response to the RRC container message. Then, MN 104A sends an SN reconfiguration complete message including the RRC reconfiguration complete message to SN 106A.

[0125] UE 102 immediately performs a random access procedure 380 on the second PSCell in response to RRC reconfiguration message 372. If SN 106A recognizes UE 102 in the random access procedure on the second PSCell, SN 106A can resume communication between UE 102 and SN via SN radio resources 384. If UE 102 successfully completes the random access procedure, UE 102 operates 384 in the DC with MN and SN, and communicates with SN 106A via the second PSCell 384. Events 334, 336, 338, and 342 can occur after event 384.

[0126] Now for reference Figure 3G Scenario 300G involves the configuration of handling conditions when a UE operating in a DC with an MN and an SN detects an SCG failure. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figure 3F and Figure 3G The differences between the scenarios.

[0127] Compared to scenario 300F, in scenario 300G, UE 102 detects a 325SCG failure and, in response to the detection of the SCG failure, releases the C-SN configuration (or conditional configuration) used for CPAC for 325, instead of retaining the C-SN configuration. SN 106A may release the C-SN configuration (or conditional configuration) in response to receiving a 326SN message (if sent by MN 104A) or in response to determining that UE 102 has disconnected from SN 106A (i.e., SN 106A determines that UE 102 has detected an SCG failure by detecting disconnection from UE 102).

[0128] In some implementations, the conditions in the conditional configuration may be associated with at least one measurement configuration (e.g., MeasConfig IE) configured to UE 102 by MN 104A. Each of the at least one measurement configuration is associated with a measurement identity (e.g., MeasIdIE). In some implementations, UE 102 may release at least one measurement configuration if UE 102 releases the 325C-SN configuration or the conditional configuration. In other implementations, UE 102 does not release at least one measurement configuration if UE 102 releases the 325C-SN configuration or the conditional configuration.

[0129] Now for reference Figure 4A Scenario 400A involves CPAC failure without SN change, specifically, a conditional change of the SN's PSCell when the UE is already operating in a DC with both MN and SN. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. The following discussion... Figures 3A-3B and Figure 4A The differences between the scenarios.

[0130] At the start of scenario 400A, UE 102 operates in an MR-DC with MN 104A and SN 106A. UE 102 transmits 402UL PDUs and / or DL ​​PDUs via PSCell (i.e., a cell different from cell 126A) and SN 106A according to a specific SN configuration. Then, UE 102, MN 104A, and SN 106A perform the above-mentioned... Figure 3A and Figure 3B The CPAC configuration program 320A or 320B is discussed.

[0131] UE 102 may later detect that 443 meets the conditions for connecting to C-PSCell 126A. In response to this detection, UE 102 may suspend 443 communication with SN 106A on PSCell and initiate 443 a random access procedure on C-PSCell 126A. UE 102 may also suspend communication with SN 106A on one or more SCells (if configured). UE 102 may fail 444 in the random access procedure on C-PSCell 126A. In response to the failure of the random access procedure, UE 102 attempts 445 to resume communication with SN on PSCell. In some implementations, to resume communication with SN 106A on PSCell, UE 102 may perform 449 a random access procedure with SN 106A via PSCell. If UE 102 successfully completes random access procedure 449, then in the MR-DC with MN 104A and SN 106A, UE 102 communicates with SN 106A via PSCell according to the SN configuration 450. That is, UE 102 resumes communication with SN 106A via PSCell. In some embodiments, UE 102 uses one or more random access configurations broadcast on PSCell (e.g., in one or more System Information Blocks (SIBs)) to perform random access procedure 449. In one embodiment, if UE 102 successfully completes random access procedure 449, then in the MR-DC with MN 104A and SN 106A, UE 102 communicates with SN 106A via one or more SCells according to the SN configuration. That is, UE 102 resumes communication with SN 106A via one or more SCells. In another implementation, if UE 102 successfully completes random access procedure 449, the UE does not communicate with SN 106A via one or more SCells according to the SN configuration until UE 102 receives a MAC control element (CE) from SN 106A that activates one or more SCells.

[0132] In other implementations, UE 102 skips event 449. To resume communication with SN 106A on the PSCell, UE 102 operates 450 in the MR-DC having MN 104A and SN 106A, and communicates with SN 106A via the PSCell according to the SN configuration 450. For example, depending on the SN configuration, UE 102 may send control signals to SN 106A on the PUCCH on the PSCell, and receive at least one Physical Downlink Control Channel (PDCCH) on the PSCell or one or more SCells. Control signals may include scheduling requests, uplink control information (UCI), or channel state information (CSI).

[0133] In some implementations, UE 102 fails in the random access procedure 444 because UE 102 does not successfully complete the random access procedure within a time period. For example, UE 102 may start a timer (e.g., T304 or T307) in response to detection 443 to count that time period. If UE 102 successfully completes the random access procedure before the timer expires, the UE stops the timer. Otherwise, the timer expires, and UE 102 fails in the random access procedure 444 (i.e., UE 102 fails in the CPAC procedure). UE 102 may determine that an SCG failure occurred when the timer expired. In some implementations, UE 102 may determine that the failure type of the SCG failure is an SCG change failure (or an SCG synchronization reconfiguration failure). In other implementations, UE 102 may determine that the failure type of the SCG failure is a conditional SCG change failure or a conditional SCG synchronization reconfiguration failure.

[0134] If UE 102 skips random access procedure 449, UE 102 may be unable to resume communication with SN 106A via PSCell 450 because UE 102 did not identify its UE identity on at least one PDCCH on PSCell within a given time period. More specifically, if UE 102 does not find a Cyclic Redundancy Check (CRC) scrambled with its UE identity on at least one PDCCH on PSCell within that time period, UE 102 may be unable to resume communication with SN 106A on PSCell 450. For example, UE 102 may start a timer (e.g., T304, T307, or a new timer T3xx) to count that time period in response to detection 443. If UE 102 successfully identifies the UE identity on at least one PDCCH on the PSCell before the timer expires (e.g., UE 102 detects a CRC scrambled with the UE identity), the UE stops the timer and determines that UE 102 has successfully resumed communication with SN 106A on the PSCell. Otherwise, the timer expires and UE 102 fails to resume communication with SN 106A on the PSCell.

[0135] In some implementations, in response to failure 444, UE 102 may send an SCG failure information message to MN 104A to notify MN 104A of the (conditional) SCG change failure. MN 104A may send an SN message to SN 106A in response to the SCG failure information message. In some implementations, MN 104A may indicate in the SN message that the conditional SCG change failed or indicate that SN 106A should release the C-SN configuration. In some implementations, the SN message may be an SN modification request message, and in response, SN 106A may send an SN modification request response message to MN 104A. In other implementations, the SN message may be an SN release request message, and in response, SN 106A may send an SN release request response message to MN 104A.

[0136] In other implementations, if UE 102 successfully resumes communication between 450 and SN 106A via PSCell, UE 102 does not send an SCG failure message. That is, UE 102 can operate as if failure 444 or detection 443 had not occurred.

[0137] In some implementations, UE 102 may retain the C-SN configuration in response to failure 444. Then, UE 102 may perform actions such as... Figure 3AEvents 334-338 and 342 are described above. In response to an SN message or in response to determining that UE 102 has disconnected from SN 106A (i.e., SN 106A determines through its detection that UE 102 has an SCG failure), SN 106A may not release the C-SN configuration.

[0138] In other implementations, UE 102 may release the C-SN configuration in response to failure 444. SN 106A may release the C-SN configuration in response to an SN message or in response to determining that UE 102 has disconnected from SN 106A.

[0139] Next, Figure 4B Scenario 400B is largely similar to Scenario 400A, and events in this scenario that are similar to those discussed above are labeled with the same reference numbers. Figure 4A and Figure 4B The differences are as follows.

[0140] In some implementations, UE 102 may attempt to resume communication with SN 106A on PSCell 445. UE 102 may fail to resume communication on PSCell as... Figure 4A The communication with SN 106A described above. If UE 102 fails to resume communication with SN 106A on PSCell, UE 102 may send a 494SCG failure information message to MN 104A. UE 102 may indicate in the SCG failure information message that the (condition) SCG change failed. MN 104A may respond as follows: Figure 4A The aforementioned SCG failure information message is used to send a 496SN message to SN 106A. If UE 102 successfully recovers on PSCell as described above... Figure 4A In one implementation of the communication with SN 106A, UE 102 may not send an SCG failure message to MN 104A. If UE 102 successfully recovers on PSCell as described above... Figure 4A In another embodiment, the communication with SN 106A may involve UE 102 sending an SCG failure message to MN 104A to notify MN 104A of the (conditional) SCG change failure.

[0141] In other implementations, UE 102 may not attempt to resume communication with SN 106A. UE 102 may send a 494SCG failure information message to MN 104A in response to failure 444. UE 102 may indicate in the SCG failure information message that the (condition) SCG change failed. MN 104A may respond as follows... Figure 4AThe aforementioned SCG failure information message triggers a 496SN message (e.g., an SN modification request message) sent to SN 106A. SN 106A may suspend communication with UE 102 via SN radio resources in response to SN message 496 or in response to determining that UE 102 has disconnected from SN 106A, such as... Figure 3A As stated above.

[0142] Turning Figure 4C In scenario 400C as described, UE 102 can retain the 447C-SN configuration in response to failure 444. Then, UE 102 can perform actions such as... Figure 3A Events 334-342 are described above. In some implementations, UE 102 may start timer 452 and wait until UE 102 detects that timer 464 has expired before executing events 334-342. SN 106A may not release the C-SN configuration in response to an SN message or in response to determining that UE 102 has disconnected from SN 106A. Alternatively, UE 102 may execute event 335 instead of event 334.

[0143] Turning Figure 4D In scenario 400D, UE 102 can release the 448C-SN configuration in response to failure 444 or 446. SN 106A can release the C-SN configuration in response to an SN message or in response to determining that UE 102 has disconnected from SN 106A (i.e., SN 106A determines through its detection that UE 102 has an SCG failure).

[0144] Next reference Figures 5A-5E Several example scenarios involving CSAC are discussed.

[0145] First refer to Figure 5A In scenario 500A, base station 104A operates as the MN, base station 106A operates as the SN, and base station 106B operates as the C-SN. At the start of this scenario, UE 102 operates 502 in a DC having MN 104A and SN 106A, transmitting UL PDUs and / or DL ​​PDUs via PCell to MN 104A, and transmitting UL PDUs and / or DL ​​PDUs via PSCell (i.e., the cell not used for cell 126A) to SN 106A. In some implementations, scenario 500A may begin with UE 102 operating 502 in an SC having MN 104A. Events 524, 526, 528, 530, and 532 are similar to events 324, 326, 328, 330, and 332.

[0146] MN 104A determines that it should configure base station 106B as the C-SN for CSAC, causing the SN of UE 102 to change from SN106B to C-SN 106B. For example, MN 104A can make this determination based on multiple measurements from UE 102, or in response to an indication from SN 106A requesting a conditional SN change (e.g., a message requesting an SN change), which SN 106A can then send to MN 104A. More intelligently, based on uplink signals received from UE 102 or multiple positioning measurements received from UE 102, MN 104A can deduce or estimate that UE 102 is moving towards the coverage area of ​​base station 106B. In response to this determination, MN 104A sends a SN request message to C-SN 106B to initiate CSAC. In response to receiving the 561SN Request message, C-SN 106B determines 562 that it should generate a C-SN configuration for CSAC for UE 102. C-SN 106B sends 563 an SN Request Response message to MN 104A including the C-SN configuration for CSAC. The C-SN configuration may include configurations for C-PSCells and for zero or more C-SCells. In some implementations, MN 104A may include the C-SN configuration message in an RRC container message. MN 104A then includes the C-SN configuration or RRC container message for CSAC in the Conditional Configuration Field / IE and sends 564 an RRC Reconfiguration message including the Conditional Configuration Field / IE to UE 102. In some implementations, UE 102 sends an 510 RRC Reconfiguration Complete message to MN 104A in response to the RRC Reconfiguration message. MN 104A may send a 512SN message (e.g., SN reconfiguration complete message or SN change confirmation message) to C-SN 106B in response to an RRC reconfiguration complete message. Events 502, 560-564, 510, and 412 together define the CSAC configuration procedure 568.

[0147] In some implementations, in event 563, C-SN 106B includes radio bearer configuration for conditional configuration in the SN request response message, and in event 564, MN 104A may further include radio bearer configuration in the RRC reconfiguration message. MN 104A may include radio bearer configuration at the level of the RRC reconfiguration message, at the level of the conditional configuration element, or at the level of the aforementioned RRC container message.

[0148] When a 564RRC reconfiguration is sent to UE 102, MN 104A may specify a condition that must be met before UE 102 applies the C-SN configuration for CSAC. Alternatively, SN 106A may specify the condition that must be met before UE 102 applies the C-SN configuration for CSAC in an instruction instructing SN 106A to request a change in the condition SN. MN 104A may include the configuration of this condition at the level of the RRC reconfiguration message, at the level of the condition configuration element, or at the level of the C-SN configuration for CSAC. In the condition configuration element of the 564RRC reconfiguration message, MN 104A may, for example, include a configuration ID to identify the C-SN configuration for CSAC.

[0149] In some implementations, the SN request message is an SN add request message, and the SN request response message is an SN add request response message. In other implementations, the SN request message is an SN modify request message, and the SN request response message is an SN modify request response message. In some implementations, MN 104A instructs base station 106B in the SN request message to request base station 106A to operate as the C-SN of UE 102. UE 102 may determine that the condition configuration includes C-SN configuration and apply the C-SN configuration to CSAC to communicate with C-SN 106B.

[0150] Later, UE 102 detects a 522SCG failure and retains the C-SN configuration for CSAC in response to the SCG failure. UE 102 sends a 524SCG failure information message to MN 104A to notify MN 104A of the SCG failure. In response to receiving the 524SCG failure information message, MN 104A may send a 526SN message to SN 106A, causing SN 106A to suspend communication with UE 102 via SN radio resources (i.e., SCG radio resources on SN 106A's PSCell and (if configured) SCells). In response to receiving the 526SN message (if sent by MN 104A) or in response to determining that UE 102 has disconnected from SN 106A, SN 106A may suspend communication with UE via SN radio resources in response to 528. Therefore, SN 106A does not expend its radio resources to attempt to send data to UE 102, which has already detected SCG failure. After SN 106A suspends communication with UE 102 via SN radio resources, for example, if SN 106A receives data packets from CN 110 (e.g., S-GW 112 or UPF 162) or an edge server, SN 106A can send 530 data PDUs (e.g., PDCP PDUs) including data packets to MN 104A. MN 104A then sends 532 data PDUs to UE 102. Thus, SN 106A sends 530 data PDUs to UE 102 via MN 104A. The data PDUs can be associated with an SN-termination bearer, which can be a separate bearer or an MCG bearer.

[0151] Generally, SCG failure may be related to the SCG radio resources used by UE 102 to communicate with SN 106A. SCG failure can be one of the following: radio link failure, SCG change failure (or SCG synchronization reconfiguration failure), SCG reconfiguration failure, and SRB3 integrity failure. UE 102 can detect an SCG failure when it detects a random access problem on the PSCell, or when timer T310 or T313 used to monitor the radio link on the PSCell expires, or when the maximum number of retransmissions with SN 106A on the SCG radio resources at the RLC layer has been reached. Furthermore, SCG change failure can correspond to immediate SCG change failure (or immediate SCG synchronization reconfiguration failure) or conditional SCG change failure (or conditional SCG synchronization reconfiguration failure). The term "SCG change" can be applied to either PSCell change or SN change. Immediate SCG synchronization reconfiguration failure occurs when UE 102 fails in an RRC reconfiguration procedure involving synchronized reconfiguration for immediate SCG changes. Conditional SCG changes can correspond to CPAC or CSAC. Conditional SCG synchronization reconfiguration failure occurs when UE102 fails during an RRC reconfiguration procedure involving synchronization reconfiguration for conditional SCG changes. This failure occurs if UE102 detects that the condition is met or the C-PSCell is appropriate (for...). Figure 3C Similarly, if UE 102 fails to connect to the C-PSCell (i.e., UE 102 fails in CPAC or CSAC) despite being described as "suitable," then UE 102 detects a 522 conditional SCG change failure (or conditional SCG synchronization reconfiguration failure). SCG reconfiguration failures can include immediate SCG reconfiguration failures and conditional SCG reconfiguration failures. If UE 102 receives an RRC reconfiguration message on an SRB (e.g., SRB3) established between UE 102 and SN 106A, and determines that the RRC reconfiguration message contains an invalid configuration not in the conditional configuration (or C-SN configuration), then UE 102 detects an immediate SCG reconfiguration failure. If UE 102 receives a C-SN configuration and identifies that the C-SN configuration is invalid (e.g., the C-SN configuration contains an invalid configuration), then UE 102 detects a conditional SCG reconfiguration failure.

[0152] Based on the above, SCG failures can be classified into 8 types (or causes): (1) random access problem, (2) timer T310 or T313 expires, (3) exceeding the maximum number of retransmissions at the RLC layer, (4) instant SCG change failure (or instant SCG synchronization reconfiguration failure), (5) conditional SCG change failure (conditional SCG synchronization reconfiguration failure), (6) instant SCG reconfiguration failure, (7) conditional SCG reconfiguration failure, and (8) SRB3 integrity failure.

[0153] In other implementations, some of the SCG failure types listed above can be combined into a single failure type. For example, immediate SCG reconfiguration failure and conditional SCG reconfiguration failure can be combined into SCG reconfiguration failure. In another example, immediate SCG change failure and conditional SCG change failure can be combined into SCG reconfiguration failure.

[0154] In some implementations, if SCG failure is the first failure type, UE 102 retains the C-SN configuration, and if SCG failure is the second failure type, UE 102 releases the C-SN configuration. For example, the second failure type could be a conditional SCG change failure or a conditional SCG reconfiguration failure, and the first failure type could be a different failure type.

[0155] Optionally, after detecting a 522SCG failure and retaining the 522C-SN configuration, UE 102 detects that 554 satisfies one or more conditions for connecting to C-PSCell 126B, and initiates a 554 random access procedure on C-PSCell 126B in response to this detection. For convenience, this discussion may refer to conditions or configurations in singular form, but it will be understood that multiple conditions may exist, and condition configurations may include one or more configuration parameters. In any case, UE 102 performs a 536 random access procedure with C-SN 106B via C-PSCell 126B using the random access configuration included in the C-SN configuration. UE 102 (if UE 102 is operating in the DC) may disconnect from SN 106A (i.e., the PSCell and all SCells of SN 106A, if configured) in response to event 554 or 536. UE 102 may send a 538RRC reconfiguration complete message to MN 104A in response to event 554 or 536. UE 102 may send the 538RRC reconfiguration complete message before or after event 536, or while UE 102 is performing the 536 random access procedure. Subsequently, MN 104A, in response to the RRC reconfiguration complete message, sends a 539SN message to C-SN 106B (e.g., an existing SN message such as the SN reconfiguration complete message or a newly defined SN message). MN 104A may or may not include the RRC reconfiguration complete message in the SN message. The newly defined SN message may be specifically designed for MN 104A to send the RRC reconfiguration complete message to C-SN 106B or to notify UE 102 to apply C-SN configuration.

[0156] In some implementations, the random access procedure may be a four-step random access procedure or a two-step random access procedure. In other implementations, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. After UE 102 successfully completes the random access procedure 536, C-SN 106B begins operating as SN 106B, and UE 102 begins operating in the DC having MN 104A and SN 106B 542. Specifically, UE 102 communicates with SN 106B via C-PSCell 126B (i.e., the new PSCell 126B) according to the C-SN configuration for CSAC 542.

[0157] In some implementations, C-SN 106B identifies UE 102 if it finds the identity of UE 102 in the Media Access Control (MAC) Protocol Data Unit (PDU) received from UE 102 during the random access procedure (Event 536). C-SN 106B includes the identity of UE 102 in its C-SN configuration. In other implementations, C-SN 106B identifies UE 102 if it receives a dedicated random access preamble from UE 102 during the random access procedure. C-SN 106B includes the dedicated random access preamble in its C-SN configuration.

[0158] The SN configuration may include multiple configuration parameters for UE 102 to communicate with SN 106A via PSCell 126A and zero or more secondary cells (SCells). These configuration parameters can configure the radio resources used by UE 102 to communicate with SN 106A via PSCell 126A and zero or more SCells. Multiple configuration parameters can also configure zero or more radio bearers. The one or more radio bearers may include SRBs and / or DRBs.

[0159] In some implementations, C-SN 106B specifies one or more conditions in the C-SN configuration used for CSAC. In other implementations, MN 104A includes the C-SN configuration and one or more conditions in the condition configuration element or RRC reconfiguration message 564. MN 104A can generate the condition configuration for UE 102A or receive the condition configuration 563 from C-SN 106B.

[0160] In some implementations, C-SN configuration includes configuring the C-PSCell 126B of C-SN 106B and zero or more C-SCells using a CellGroupConfig IE. In one implementation, the C-SN configuration may be an RRCReconfiguration message, RRCReconfiguration-IE, or CellGroupConfigIE conforming to 3GPP TS 38.331. In other implementations, C-SN configuration includes configuring the C-PSCell using an SCG-ConfigPartSCG-r12 IE, and may configure zero or more C-SCells of C-SN 106B. In one implementation, the C-SN configuration is an RRCConnectionReconfiguration message, RRCConnectionReconfiguration-IE, or ConfigPartSCG-r12 IE conforming to 3GPP TS 36.331.

[0161] In some implementations, the SN configuration includes a CellGroupConfig IE for configuring the PSCell, and can be zero or one or more SCells of SN106A. In one implementation, the SN configuration can be an RRCReconfiguration message, RRCReconfiguration-IE, or CellGroupConfig IE conforming to 3GPP TS 38.331. In other implementations, the SN configuration can include an SCG-ConfigPartSCG-r12 IE for configuring the PSCell, and can be zero or one or more SCells of SN 106A. In one implementation, the SN configuration can be an RRCConnectionReconfiguration message, RRCConnectionReconfiguration-IE, or ConfigPartSCG-r12 IE conforming to 3GPP TS 36.331.

[0162] In some cases, UE 102 receives one or more conditions in a 564 Condition Configuration or RRC Reconfiguration message. UE 102 can use one or more conditions to determine whether to connect to C-PSCell 126B. If UE 102 detects that a condition is met, UE 102 connects to C-PSCell 126B. That is, the condition (also known as the trigger condition) triggers UE 102 to connect to C-PSCell 126B or perform C-SN configuration. If UE 102 does not detect that a condition is met, UE 102 does not connect to C-PSCell 126B.

[0163] In some implementations, C-SN 106B may include CU 172 and one or more DU 174, such as Figure 1C As shown. CU 172 receives an SN request message from MN 104A and sends an SN request response message. DU 174 can generate a C-SN configuration or a portion thereof (e.g., the identity of UE 102, a dedicated random access preamble, a random access configuration), and send the C-SN configuration or a portion thereof to CU 172. If DU 174 generates a portion of the C-SN configuration, CU 172 can generate the remainder of the C-SN configuration. In one embodiment, DU 174 can perform a random access procedure with UE 102 (536), and identify UE 102 during the random access procedure. In response to this identification, DU 174 communicates with UE 102 using the C-SN configuration or a portion thereof. In another embodiment, DU 174 can perform a random access procedure with UE 102 (536), and forward the identity of UE 102 received in the MAC PDU to CU 172 during the random access procedure. CU 172 identifies UE 102 based on its identity. In response to this identification, CU 172 and DU 174 communicate with UE 102 using a portion of the C-SN configuration and the remainder of the C-SN configuration, respectively.

[0164] If C-SN 106B identifies UE 102 on C-PSCell 126B during random access procedure 536, C-SN 106B begins to send (multiple) downlink control information (DCI) commands, (multiple) reference signals, or data on the Physical Downlink Control Channel (PDCCH) to UE 102 via C-PSCell 126B and / or one or more C-SCells (if configured in the C-SN configuration), according to some configuration parameters in the C-SN configuration. If C-SN 106B identifies UE 102 on C-PSCell 126B during random access procedure 536, C-SN 106B may, according to some configuration parameters in the C-SN configuration, receive from UE 102, via C-PSCell 126B and / or one or more C-SCells (if configured in the C-SN configuration), multiple signals, multiple probe reference signals, or data on the Physical Uplink Control Channel (PUCCH). UE 102 may, according to some configuration parameters in the C-SN configuration, receive from C-SN 106B, via C-PSCell 126B and / or one or more C-SCells (if configured in the C-SN configuration), multiple DCI commands, multiple reference signals, or data on the PDCCH. UE 102 can transmit multiple signals, multiple probe reference signals, or data on the PUCCH to C-SN 106B via C-PSCell 126B and one or more C-SCells (if configured in the C-SN configuration) according to some configuration parameters in the C-SN configuration. In response to this identification, C-SN 106B becomes SN 106B, C-PSCell 126B becomes PSCell 126B, and one or more C-SCells become one or more SCells.

[0165] As described above, MN 104A and C-SN 106B configure C-PSCell 126B for UE 102 before C-PSCell 126B becomes suitable for UE 102. UE 102 retains the C-SN configuration in response to detecting an SCG failure. When C-PSCell 126B becomes suitable for UE 102 (i.e., UE 102 detects a corresponding condition), UE 102 performs a random access procedure with the C-PSCell to quickly change the PSCell (i.e., change the SN). Compared to an instant SN addition procedure, the conditional SN addition technique discussed in this disclosure significantly reduces the latency associated with DC configuration.

[0166] Now for reference Figure 5BScenario 500B is generally similar to Scenario 500A, and events similar to those discussed above are labeled with the same reference numbers. However, in this scenario, UE 102 starts a timer to determine whether to notify MN104A of SCG failure.

[0167] The UE detects a 522SCG failure and retains the C-SN configuration for CSAC. Unlike scenario 500A, UE 102 does not initiate an SCG failure report upon detecting an SCG failure. Instead, UE 102 starts a 552SCG failure recovery timer in response to an SCG failure (e.g., upon detecting an SCG failure). Before the SCG failure timer expires, UE 102 detects that 554 meets the conditions for connecting to C-PSCell 126B or that C-PSCell 126B is suitable, and initiates a 554 random access procedure on C-PSCell 126B in response to this detection. UE 102 then (e.g., using one or more random access configurations in the C-SN configuration) performs a 536 random access procedure with C-SN 106B via C-PSCell 126B. If UE102 successfully completes the random access procedure, UE102 stops the 560SCG failure recovery timer and communicates with C-SN 106B via C-PSCell 126B according to the configuration in the C-SN configuration 542. If UE102 does not detect that the conditions for connecting to C-PSCell 126B are met or that C-PSCell 126B is suitable before detecting that the 564SCG failure recovery timer has expired, events 524-532, 554, and 536-542 may occur.

[0168] Now for reference Figure 5C Scenario 500C is generally similar to Scenario 500A, and events similar to those discussed above are labeled with the same reference numbers. In this scenario, UE 102 detects a 523SCG failure and sends a 524SCG failure information message. When UE 102 detects the 523SCG failure, UE 102 has not yet received the CSAC configuration procedure from MN 104A. In this scenario, after receiving the SCG failure information message indicating that the UE has detected an SCG failure, MN 104A provides 568 for CSAC conditional configuration.

[0169] Now for reference Figure 5DScenario 500D involves configuring handling conditions when a UE operating in an SC with an MN or in a DC with both an MN and an SN detects an SCG failure. In this scenario, base station 104A operates as the MN, base station 106A operates as the SN, and base station 106B operates as the C-SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figure 5A and Figure 5D The differences between the scenarios.

[0170] Similar to scenario 500A, UE 102 detects a 521SCG failure and retains the C-SN configuration for CSAC. However, in scenario 500D, UE 102 suspends 521CSAC operation in response to the SCG failure. After UE 102 suspends CSAC operation, UE 102 can stop detecting conditions for connecting to C-PSCell 126B, or stop connecting to C-PSCell 126B if UE 102 detects that the conditions for connecting to C-PSCell 126B are met.

[0171] In some implementations, UE 102 may include at least one measurement result in the SCG failure information message 524, and MN 104A may then send at least one measurement result to SN 106A in the SN message 526. In other implementations, after UE 102 detects an SCG failure, UE 102 may send at least one measurement report message including at least one measurement result to SN 106A via MN 104A. In other implementations, after UE 102 detects an SCG failure, UE 102 may send at least one measurement report message including at least one measurement result to MN 104A.

[0172] If at least one measurement associated with the second PSCell is higher than a threshold, SN 106A may execute the SN modification procedure of 570 and MN 104A to configure UE 102 to perform an immediate PSCell change to the second PSCell (e.g., the first PSCell at event 502 or a new PSCell). In the SN modification procedure, SN 106A sends a request SN modification message to MN 104A, and MN 104A may respond with an SN modification confirmation message. MN 104A may send an SN modification request message to SN 106A in response to the request SN modification message, and in response, SN 106A may send an SN modification request response message.

[0173] Alternatively, if at least one measurement associated with the second PSCell is above a threshold, MN 104A can initiate and execute an SN modification procedure with SN 106A at 570 to configure UE 102 to perform an immediate PSCell change to the second PSCell (e.g., the first PSCell at event 502 or a new PSCell). In the SN modification procedure, MN 104A can send an SN modification request message to SN 106A, and in response, SN 106A can send an SN modification request response message. The SN message at event 526 can be an SN modification request message, such that the SN message at event 526 can be part of the SN modification procedure.

[0174] In an RRC reconfiguration message (e.g., a request for SN modification message or an SN modification request response message), SN 106A configures UE 102 to perform an immediate PSCell change to the second PSCell. Then, MN 104A sends a 572 RRC reconfiguration message to UE 102. In one implementation, at event 572, MN 104A may send an RRC container message to UE 102 including the RRC reconfiguration message. If MN 104A does not configure UE 102 to release the C-SN configuration in the RRC container message, UE 102 resumes 574 CSAC operation in response to the RRC container message. After UE 102 resumes CSAC operation, UE 102 may begin detecting conditions for connecting to C-PSCell 126B, or connect to C-PSCell 126B if UE 102 detects that the conditions for connecting to C-PSCell 126B are met. If UE 102 detects conditions for connecting to C-PSCell 126B before completing random access procedure 580, UE 102 can connect to C-PSCell 126B after completing the random access procedure. Alternatively, UE 102 can resume CSAC operation 574 after completing random access procedure 380.

[0175] If MN 104A determines to release the C-SN configuration, then MN 104A executes the C-SN release procedure 571 with C-SN 106B. In the C-SN release procedure, MN 104A sends an SN release request message to C-SN 106B to instruct C-SN 106B to release the C-SN configuration. C-SN 106B may send an SN release request response message to MN 104A in response to the SN release request message. In response to this determination, MN 104A configures UE 102 to release the C-SN configuration in an RRC container message, and UE 102 releases the C-SN configuration in response to the RRC container message 574. MN 104A may execute the SN modification procedure 570 and the C-SN release procedure 517 in parallel or sequentially.

[0176] UE 102 sends an RRC reconfiguration complete message (576) to MN 104A in response to the RRC reconfiguration message, and MN 104A can then send an SN message (578) including the RRC reconfiguration complete message to SN 106A. In one embodiment, UE 102 sends an RRC container response message (576) including the RRC reconfiguration complete message in response to the RRC container message. The SN message (578) sent by MN 104A can be an SN modification confirmation message or an SN reconfiguration complete message. In some embodiments, MN 104A can include the RRC reconfiguration message in the RRC container message and send the RRC container message to UE 102. UE 102 can include the RRC reconfiguration complete message in the RRC container response message and send an RRC container response message to MN 104A in response to the RRC container message. Then, MN 104A sends an SN reconfiguration complete message or an SN modification confirmation message including the RRC reconfiguration complete message to SN 106A.

[0177] UE 102 immediately performs a random access procedure 580 on the second PSCell in response to RRC reconfiguration message 572. If SN 106A recognizes UE 102 in the random access procedure on the second PSCell, SN 106A can resume communication between UE 102 and SN via SN radio resources 584. If UE 102 successfully completes the random access procedure, UE 102 operates 584 in the DC with MN and SN, and communicates with SN 106A via the second PSCell 584. Events 554 and 536-542 can occur after event 584.

[0178] Now for reference Figure 5EScenario 500E involves the configuration of handling conditions when a UE detects an SCG failure in an SC with an MN or in a DC with both an MN and an SN. In this scenario, base station 104A operates as the MN, base station 106A operates as the SN, and base station 106B operates as the C-SN. In this scenario, events similar to those discussed above are labeled with the same reference numerals. The following discussion... Figure 5A and Figure 5D and Figure 5E The differences between the scenarios.

[0179] Compared to scenario 500D, in scenario 500E, UE 102 detects a 525SCG failure and releases the 525C-SN configuration (or conditional configuration) in response to the SCG failure, instead of retaining the C-SN configuration. MN 104A does not require UE 102 to be explicitly configured to release the C-SN configuration in the RRC container message.

[0180] Now for reference Figure 6A Scenario 600A involves a failure related to CSAC. In this scenario, base station 104A operates as the MN, and base station 106A operates as the SN. The following discussion... Figure 5A and Figure 6A The differences between the scenarios.

[0181] At the start of scenario 600A, UE 102 operates in an MR-DC with MN 104A and SN 106A. UE 102 transmits 602UL PDUs and / or DL ​​PDUs via PSCell (i.e., a cell different from cell 126A) and SN 106A according to a specific SN configuration. Then, UE 102, MN 104A, and SN 106A perform the above-mentioned... Figure 5A The CSAC configuration procedure is discussed.

[0182] UE 102 may later detect that 643 meets the conditions for connecting to C-PSCell 126B. In response to this detection, UE 102 may suspend 643's communication with SN 106A on the PSCell and initiate a random access procedure 643 on C-PSCell 126B. UE 102 may also suspend communication with SN 106A on one or more SCells (if configured). UE 102 may fail 644 in the random access procedure on C-PSCell 126B. In response to the failure of the random access procedure, UE 102 attempts 645 to resume communication with SN on the PSCell. In some implementations, to resume communication with SN 106A on the PSCell, UE 102 may perform 649 the random access procedure with SN 106A via the PSCell. In some implementations, UE 102 performs the random access procedure 649 using one or more random access configurations broadcast on the PSCell (e.g., in one or more System Information Blocks (SIBs)). If UE 102 successfully completes the random access procedure 649, then in the MR-DC with MN 104A and SN 106A, UE 102 communicates with SN 106A via the PSCell according to the SN configuration 650. That is, UE 102 resumes communication with SN 106A via the PSCell. In one implementation, if UE 102 successfully completes the random access procedure 649, then in the MR-DC with MN 104A and SN 106A, UE 102 can also communicate with SN 106A via one or more SCells according to the SN configuration. That is, UE 102 resumes communication with SN 106A via one or more SCells. In another implementation, if UE 102 successfully completes random access procedure 649, the UE does not communicate with SN 106A via one or more SCells according to the SN configuration until UE 102 receives a MAC control element (CE) from SN 106A that activates one or more SCells.

[0183] In other implementations, UE 102 skips event 649. To resume communication with SN 106A on the PSCell, UE 102 operates 650 in the MR-DC having MN 104A and SN 106A, and communicates with SN 106A via the PSCell according to the SN configuration 650. For example, depending on the SN configuration, UE 102 may send control signals to SN 106A on the PUCCH on the PSCell, and receive at least one Physical Downlink Control Channel (PDCCH) on the PSCell or one or more SCells. Control signals may include scheduling requests, uplink control information (UCI), or channel state information (CSI).

[0184] In some implementations, UE 102 may fail in the random access procedure 644 because UE 102 does not successfully complete the random access procedure within a time period. For example, UE 102 may start a timer (e.g., T304 or T307) in response to detection 643 to count that time period. If UE 102 successfully completes the random access procedure before the timer expires, the UE stops the timer. Otherwise, the timer expires, and UE 102 fails in the random access procedure 644 (i.e., UE 102 fails in the CSAC procedure). UE 102 may determine that an SCG failure occurred when the timer expired. In some implementations, UE 102 may determine that the failure type of the SCG failure is an SCG change failure (or an SCG synchronization reconfiguration failure). In other implementations, UE 102 may determine that the failure type of the SCG failure is a conditional SCG change failure or a conditional SCG synchronization reconfiguration failure.

[0185] If UE 102 skips random access procedure 649, at event 650, UE 102 may be unable to resume communication with SN 106A via PSCell because UE 102 did not identify its UE identity on at least one PDCCH on PSCell within a given time period. More specifically, if UE 102 does not find a Cyclic Redundancy Check (CRC) scrambled with its UE identity on at least one PDCCH on PSCell within that time period, UE 102 may be unable to resume communication with SN 106A on PSCell. For example, UE 102 may start a timer (e.g., T304, T307, or a new timer T3xx) to count that time period in response to detection 643. If UE 102 successfully identifies the UE identity on at least one PDCCH on the PSCell before the timer expires (e.g., UE 102 detects a CRC scrambled with the UE identity), the UE stops the timer and determines that UE 102 has successfully resumed communication with SN 106A on the PSCell. Otherwise, the timer expires and UE 102 fails to resume communication with SN 106A on the PSCell.

[0186] In some implementations, UE 102 may send an SCG failure information message to MN 104A in response to failure 644 to notify MN 104A of the (conditional) SCG change failure. In other implementations, UE 102 may not send an SCG failure information message, as if failure 644 had not occurred or the CSAC procedure had not occurred.

[0187] In some implementations, UE 102 may retain the C-SN configuration in response to failure 644. UE 102 can then perform actions such as... Figure 5A Events 554 and 536-542 are mentioned above. In other embodiments, UE 102 may release the C-SN configuration in response to failure 644.

[0188] Next, Figure 6B Scenario 600B is largely similar to Scenario 600A, and events in this scenario that are similar to those discussed above are labeled with the same reference numbers. Figure 6A and Figure 6B The differences are as follows.

[0189] At the start of scenario 600B, the UE in the SC communicates 603 in the SC with MN 104A, or operates 603 in the DC with MN 104A and SN 106A, and communicates 603 with SN 106A via PSCell according to the SN configuration. In some implementations, UE 102 may attempt 645 to resume communication with SN 106A on PSCell. Figure 6A As described above, UE 102 may fail to resume communication with SN 106A on PSCell (644). If UE 102 fails to resume communication with SN 106A on PSCell, UE 102 may send a 694 SCG failure information message to MN 104A. In other embodiments, UE 102 may not attempt to resume communication with SN 106A. UE 102 may send a 694 SCG failure information message to MN 104A in response to failure (644).

[0190] UE 102 can indicate (condition) SCG change failure in the SCG failure information message. MN 104A can send a 697SN message to C-SN 106B in response to the SCG failure information message. MN 104A can also send a 696SN message to SN 106A in response to the SCG failure information message. In response to SN message 696 or in response to determining that UE 102 has disconnected from SN 106A (i.e., SN 106A determines through its detection that UE 102 has an SCG failure), SN 106A can suspend communication with UE 102 via SN radio resources, such as... Figure 3A As stated above.

[0191] In some implementations, MN 104A instructs C-SN 106B in SN message 697 that C-SN configuration should be released. In one implementation, SN message 697 may be an SN release request message, and in response, C-SN 106B may send an SN release request response message to MN 104A. In this case, UE 102 may release C-SN configuration in response to failure 644 or 646. Alternatively, MN 104A may send an RRC reconfiguration message to UE 102 instructing UE 102 to release C-SN configuration, and in response to the RRC reconfiguration message, UE 102 releases C-SN configuration and sends an RRC reconfiguration complete message to MN 104A. When MN 104A is implemented as an eNB or ng-eNB, the RRC reconfiguration message is an RRCConnectionReconfiguration message, and the RRC reconfiguration complete message is an RRCConnectionReconfigurationComplete message. When MN 104A is implemented as a gNB, the RRC reconfiguration message is the RRCReconfiguration message, and the RRC reconfiguration completion message is the RRCReconfigurationComplete message.

[0192] In some implementations, MN 104A instructs SN 106A in SN message 696 that SN configuration should be released (i.e., the MR-DC of UE 102 should be released). In one implementation, SN message 696 may be an SN release request message, and in response, SN 106A may send an SN release request response message to MN 104A. MN 104A may send an RRC reconfiguration message to UE 102 instructing UE 102 to release the MR-DC. UE 102 may release the MR-DC (i.e., release the SN configuration) in response to the RRC reconfiguration message and send an RRC reconfiguration complete message to MN 104A. When MN 104A is implemented as an eNB or ng-eNB, the RRC reconfiguration message is an RRCConnectionReconfiguration message, and the RRC reconfiguration complete message is RRCConnectionReconfigurationComplete. When MN 104A is implemented as a gNB, the RRC reconfiguration message is the RRCReconfiguration message, and the RRC reconfiguration completion message is the RRCReconfigurationComplete message.

[0193] In other implementations, MN 104A may instruct SN 106A to reconfigure UE 102. In one implementation, SN message 696 may be an SN modification request message, and in response, SN 106A may send an SN modification request response message to MN 104A. SN 106A may reconfigure UE 102 to connect to a second PSCell (e.g., the PSCell at event 603 or a new PSCell) in the RRC reconfiguration message within the SN modification request response message. Furthermore, MN 104A sends an RRC reconfiguration message to UE 102. UE 102 performs a random access procedure with SN 106A on the second PSCell according to one or more random access configurations in the RRC reconfiguration message. During or after the random access procedure, UE 102 sends an RRC reconfiguration complete message to MN 104A. In order to send the RRC reconfiguration message generated by SN 106A, in one implementation, MN 104A sends an RRC container message including the RRC reconfiguration to UE 102. In response, in one implementation, UE 102 sends an RRC container response message, including an RRC reconfiguration complete message, to MN 104A to send the RRC reconfiguration complete message. When SN 106A is implemented as an ng-eNB, the RRC reconfiguration message generated by SN 106A is an RRCConnectionReconfiguration message, and the RRC reconfiguration complete message is an RRCConnectionReconfigurationComplete message. When SN 106A is implemented as a gNB, the RRC reconfiguration message generated by SN 106A is an RRCReconfiguration message, and the RRC reconfiguration complete message is an RRCReconfigurationComplete message. When MN 104A is implemented as an eNB or ng-eNB, the RRC container message is an RRCConnectionReconfiguration message, and the RRC container response message is an RRCConnectionReconfigurationComplete message. When MN 104A is implemented as a gNB, the RRC container message is the RRCReconfiguration message, and the RRC container response message is the RRCReconfigurationComplete message.

[0194] In some implementations, UE 102 can retain the C-SN configuration in response to failure 644. Then UE 102 can perform actions such as... Figure 5AEvents 554 and 536-542 are mentioned above. In this case, MN 104A may not send SN message 697 to C-SN 106B.

[0195] To further clarify, please refer to the following... Figures 7-16 Let's discuss Figure 1A and Figure 1B Several example methods can be implemented by devices operating in the system.

[0196] First refer to Figure 7 Example method 700 for managing condition configuration can be found in, for example... Figure 1A and Figure 1B The instruction set is implemented in a suitable UE such as UE 102 as stored on a computer-readable medium and executable by processing hardware (e.g., one or more processors). For convenience, method 700 is discussed below with reference to UE 102.

[0197] Method 700 begins at box 702, in which UE 102 performs DC communication on PCell and PSCell. Figures 3A-3G Event 302; Figures 4A-4D Event 402; Figures 5A-5E Event 502; Figure 6A Event 602; Figure 6B Event 603). Next, at box 704, UE 102 detects SCG failure ( Figures 3A-3D Event 322; Figure 3E Event 323; Figure 3F Event 321; Figure 3G Event 325; Figures 5A-5B Event 522; Figure 5C Event 523; Figure 5D Event 521; Figure 5E Incident 525).

[0198] At box 706, UE 102 determines whether UE 102 has received information for purposes such as CPAC (…). Figures 3A-3G , Figures 4A-4D Event 320A or 320B) or CSAC ( Figures 5A-5E , Figures 6A-6B Conditional configurations for events like 568. Figure 3E and Figure 5C As shown, if UE 102 does not receive the conditional configuration, the process proceeds to block 716. Otherwise, as... Figure 3D and Figure 5B As shown, the process proceeds to box 708.

[0199] At box 708, UE 102 determines whether UE 102 has detected that the conditions for connecting to the C-PSCell are met or that the C-PSCell is suitable. Figure 3D Event 354; Figure 5B Event 554). If UE 102 does not detect that the conditions for connecting to C-PSCell are met, or if C-PSCell is suitable, the process proceeds to box 716. Otherwise, the process proceeds to box 710.

[0200] At box 710, UE 102 performs a random access procedure on C-PSCell. Figure 3D Event 336; Figure 5B Event 536). At box 712, UE 102 determines whether the random access procedure has been successfully completed. If the random access procedure has not been successfully completed, the process proceeds to box 716. Otherwise, the process proceeds to box 714.

[0201] At box 714, the UE performs DC communication on the PCell and C-PSCell. Figure 3D Event 342; Figure 3B Event 542). On the other hand, at box 716, UE 102 sends an SCG failure message to MN ( Figure 3E Event 324; Figure 5C (Event 524).

[0202] Now for reference Figure 8 An example method 800 for managing condition configuration after detecting an SCG failure can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 800 is discussed below with reference to UE 102.

[0203] Method 800 begins at block 802, in which UE 102 performs DC communication on PCell and PSCell. Figures 3A-3E Event 302; Figures 4A-4D Event 402; Figures 5A-5E Event 502; Figure 6A Event 602). Next, at box 804, UE 102 receives information for events such as CPAC (…). Figures 3A-3D , Figures 3F-3G , Figures 4A-4D Event 320A or 320B) or CSAC ( Figures 5A-5B , Figures 5D-5E , Figures 6A-6B Conditional configuration for events like 568.

[0204] At box 806, UE 102 detected an SCG failure. Figures 3A-3D Event 322; Figure 3F Event 321; Figure 3G Event 325; Figures 5A-5B Event 522; Figure 5D Event 521; Figure 5E Event 525). Next, at box 808, UE102 retains the conditional configuration ( Figures 3A-3C Event 322; Figure 5A Event 522). At box 809, UE 102 responds to this detection by sending a first SCG failure message to MN ( Figures 3A-3C Event 324; Figure 5A (Event 524).

[0205] At box 810, UE 102 detects that the conditions for connecting to the C-PSCell are met or the C-PSCell is suitable. Figures 3A-3B Event 334, Figure 3C Event 335, Figure 5A Event 554). At box 812, UE 102 performs a random access procedure on C-PSCell ( Figures 3A-3C Event 336, Figure 5A Event 536).

[0206] At box 814, UE 102 determines whether the random access procedure was completed successfully. If the random access procedure was unsuccessful, the process proceeds to box 818. Otherwise, the process proceeds to box 816.

[0207] At box 816, UE 102 performs DC communication on PCell and C-PSCell. Figures 3A-3C Event 342; Figure 5A Event 542). Alternatively, if the process proceeds to block 818, UE 102 sends a second SCG failure information message to the PCell. In some implementations, UE 102 may detect an SCG failure regarding communication on the PSCell and indicate the SCG failure as an immediate SCG failure in the first SCG failure information message. UE 102 may indicate a conditional SCG failure in the second SCG failure information message. In some implementations, UE 102 includes a field or information element in the second SCG failure information message to indicate a conditional SCG failure, but does not include a field or information element to indicate an immediate SCG failure.

[0208] Figure 9An example method 900 is shown for notifying the RAN of SCG failure by utilizing additional information indicating that the UE has failed to connect to the C-PSCell when the UE is operating in an MR-DC. This method can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 900 is discussed below with reference to UE 102.

[0209] Method 900 begins at block 902, in which UE 102 performs DC communication on PCell and PSCell. Figures 3A-3E Event 302; Figures 4A-4D Event 402; Figures 5A-5E Event 502; Figure 6A Event 602). Next, at box 904, UE 102 receives information for events such as CPAC (…). Figures 3A-3D , Figures 3F-3G , Figures 4A-4D Event 320A or 320B) or CSAC ( Figures 5A-5B , Figures 5D-5E , Figures 6A-6B Conditional configuration for events like 568.

[0210] At box 906, UE 102 detects a communication failure with the SN on the PSCell or C-PSCell. Figures 3A-3D Event 322; Figure 3F Event 321; Figure 3G Event 325; Figures 4A-4D Event 444; Figures 5A-5B Event 522; Figure 5D Event 521; Figure 5E Event 525; Figures 6A-6B Event 644). At box 908, UE 102 determines whether the communication failure with the SN is due to a failure to connect to the C-PSCell. If the failure is not due to a failure to connect to the C-PSCell, the process proceeds to box 912. If the failure is due to a failure to connect to the C-PSCell ( Figures 4A-4D Event 444; Figures 6A-6B If event 644 occurs, the process proceeds to frame 910.

[0211] UE 102 indicates in block 910, in the SCG failure information message, that the communication failure with the SN was due to the inability to connect to the C-PSCell, and sends an SCG failure information message to the MN in block 912. Figures 4B-4D Event 494; Figure 6BEvent 694). If the process proceeds from box 908 to box 912, UE 102 also sends an SCG failure message to MN ( Figures 3A-3C , Figures 3F-3G Event 324; Figure 5A , Figures 5D-5E (Event 524).

[0212] Figure 10 This is a flowchart of an example method 1000 for determining whether to notify the RAN of a failure of a conditional procedure, which can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 1000 is discussed below with reference to UE 102.

[0213] Method 1000 begins at box 1002, where UE 102 receives signals for applications such as CPAC (…). Figures 3A-3G , Figures 4A-4D Event 320A or 320B) or CSAC ( Figures 5A-5E , Figures 6A-6B The conditional configuration of the procedure (such as event 568) is then performed. Next, at box 1004, UE 102 detects a failure. At box 1006, UE 102 determines whether the failure is an MCG failure or an SCG failure. If the failure is an SCG failure, the procedure proceeds to box 1012. If the failure is an MCG failure, the procedure proceeds to box 1008. In some implementations, the MCG failure may be related to the MCG radio resources used by UE 102 to communicate with MN 104A. An MCG failure can be, for example, a radio link failure, a handover failure (or an MCG synchronization reconfiguration failure), an MCG reconfiguration failure, or an SRB1 or SRB2 integrity failure. UE 102 can detect an MCG failure while communicating with MN 104A.

[0214] At box 1008, UE 102 determines whether a conditional procedure can be used to recover from the failure. If the failure cannot be recovered, the procedure proceeds to box 1012. Otherwise, the procedure proceeds to box 1010.

[0215] At block 1010, UE 102 sends an RRC message that does not indicate failure to MN. Conversely, at block 1012, UE 102 sends an RRC message indicating failure. In some implementations, the RRC message at block 1010 is an RRC reconfiguration complete message (e.g., an RRCConnectionReconfigurationComplete message or an RRCReconfigurationComplete message), and the RRC message at block 1012 is an SCG failure information message (e.g., an SCG FailureInformation message). In some implementations, after detecting an MCG failure, UE 102 may detect that conditions for connecting to a candidate PCell (C-PCell) are met, or that the C-PCell is suitable. UE 102 may recover from the MCG failure by connecting to the C-PCell in response to this detection. To connect to the C-PCell, UE 102 performs a random access procedure on the C-PCell and sends an RRC reconfiguration complete message on the C-PCell during or after the random access procedure. If the conditional configuration includes one or more random access configurations, UE 102 can use one or more random access configurations to perform a random access procedure. If the conditional configuration includes one or more random access configurations, UE 102 can use one or more random access configurations in one or more system information blocks broadcast on the C-PCell. In some implementations, UE 102 can use one or more random access configurations in the conditional configuration and one or more SIBs to perform a random access procedure. If UE 102 successfully completes the random access procedure, UE 102 transmits data on the C-PCell. If UE 102 fails in the random access procedure, UE 102 can perform an RRC connection reconstruction procedure in which UE 102 sends an RRC reconstruction request message (e.g., an RRCConnectionReestablishmentRequest message or an RRCReestablishmentRequest message) to the cell.

[0216] Now for reference Figure 11 The example method 1100 for configuring conditional configuration after detecting an SCG failure can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 1100 is discussed below with reference to UE 102.

[0217] Method 1100 begins at block 1102, in which UE 102 communicates in a DC having MN and SN. Figure 3E Event 302; Figure 5C Event 502). Next, at box 1104, UE 102 detects SCG failure ( Figure 3E Event 323; Figure 5C Event 523). At box 1106, UE 102 responds to this detection by sending an SCG failure information message to MN indicating SCG failure. Figure 3E Event 324; Figure 5C (Event 523).

[0218] At box 1108, after sending the SCG failure information message, UE 102 receives information for purposes such as CPAC (…). Figure 3E Event 320A) or CSAC ( Figure 5C Conditional configurations for events like event 568. For example, UE 102 can receive conditional configurations from the MN. At block 1110, UE 102 detects that the conditions for connecting to the C-PSCell are met. Figure 3E Event 334; Figure 5C Event 554). In response to this detection, at box 1112, UE 102 performs a random access procedure on C-PSCell ( Figure 3E Event 336; Figure 5C Event 536). After box 1112, method 1100 can continue in a similar manner to method 800 in boxes 814-818.

[0219] Figure 12 An example method 1200 for managing condition configuration after an SCG failure is detected is shown, which can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 1200 is discussed below with reference to UE 102.

[0220] Method 1200 begins at block 1202, in which the UE communicates in the DC with the MN on the PCell and the SC on the first PSCell. Figure 3F Event 302; Figure 5D Event 502). Next, at box 1204, UE 102 receives information for events such as CPAC (…). Figure 3F 320A or 320B) or CSAC ( Figure 5D Conditional configurations for procedures like (568). At box 1206, UE102 detects an SCG failure ( Figure 3F Event 321; Figure 5D Incident 521).

[0221] At box 1208, UE 102 retains conditional configuration ( Figure 3F Event 321; Figure 5D Event 521). Next, at box 1209, UE 102 sends an SCG failure information message to MN indicating SCG failure ( Figure 3F Event 324; Figure 5D Event 524). At box 1210, UE 102 suspends conditional operation ( Figure 3F Event 321; Figure 5D Incident 521).

[0222] At box 1212, UE 102 receives an RRC reconfiguration message configuring the second PSCell. Figure 3F Event 372; Figure 5D Event 572). At box 1214, UE 102 determines whether the RRC reconfiguration message configured UE 102 to release conditional configuration. If yes, the process proceeds to box 1216, where UE 102 releases the conditional configuration. If not, the process proceeds to box 1218, where UE 102 resumes conditional operation.

[0223] From box 1216 or box 1218, the procedure proceeds to box 1220. At box 1220, UE 102, in response to the RRC reconfiguration message, performs a random access procedure on the second PSCell. Figure 3F Event 380; Figure 5D (Event 580).

[0224] Figure 13 This is a flowchart of an example method 1300 for managing condition configuration after an SCG failure is detected, which can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 1300 is discussed below with reference to UE 102.

[0225] Method 1300 begins at block 1302, in which UE 102 receives conditional configuration of the C-PSCell. Figure 4D Event 320A or 320B). At box 1304, UE 102 detects a communication failure with the SN on the PSCell or C-PSCell. Next, at box 1306, UE 102 determines whether the communication failure with the SN was due to a failure to connect to the C-PSCell. If the failure was not due to a failure to connect to the C-PSCell, the procedure proceeds to box 1310, where UE 102 retains the conditional configuration. Otherwise, the procedure proceeds to box 1308, where UE 102 releases the conditional configuration. Figure 4DEvent 448) or suspend the conditional operation used to connect to the C-PSCell. In some scenarios, before or after box 1308, in response to determining that the communication failure with the SN was due to the failure to connect to the C-PSCell, UE 102 may perform steps similar to boxes 910-912 of method 900.

[0226] Figure 14 This is a flowchart of an example method 1400 for restoring communication after a failure to connect to the C-PSCell, which can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 1400 is discussed below with reference to UE 102.

[0227] Method 1400 begins at block 1402, in which UE 102 communicates in a DC having MN and SN. Figures 4A-4B Event 402; Figures 6A-6B Event 602 or 603). At box 1404, UE 102 receives information for events such as CPAC (…). Figures 4A-4B 320A or 320B) or CSAC ( Figures 6A-6B Conditional configuration procedures such as 568). At box 1406, UE 102 detects that the conditions for connecting to the C-PSCell are met (…). Figures 4A-4B Event 443; Figures 6A-6B Event 643).

[0228] At box 1408, in response to this detection, UE 102 performs a random access procedure on C-PSCell. Figures 4A-4B Event 443; Figures 6A-6B Event 643). Next, at box 1410, UE 102 fails in the random access procedure on C-PSCell ( Figures 4A-4B Event 444; Figures 6A-6B Event 644).

[0229] At box 1412, UE 102 attempts to resume communication with SN. Figures 4A-4B Event 445; Figures 6A-6B Event 645). Next, at box 1414, UE 102 determines whether communication with the SN has been successfully resumed. If so, the procedure proceeds to box 1416, where UE 102 communicates in the DC with MN and SN. Figure 4A Event 450; Figure 6A Event 650). Otherwise, the process proceeds to box 1418, in which UE 102 sends an SCG failure message to MN ( Figure 4B Event 494; Figure 6B (Event 694). Similar to blocks 910-912 of method 900, the UE can indicate in the sent SCG failure information message that the communication failure was due to the inability to connect to the C-PSCell.

[0230] Now for reference Figure 15 An example method 1500 for managing communication with the UE after detecting an SCG failure can be implemented in the RAN of this disclosure as a set of instructions stored on a computer-readable medium and executable by, for example, processing hardware (e.g., one or more processors).

[0231] Method 1500 begins at block 1502, in which the RAN communicates with the UE (such as UE 102) via SN radio resources. Figures 3A-3D Event 302; Figures 5A-5B Event 502). Next, at box 1504, the RAN sends a message to the UE for events such as CPAC (…). Figures 3A-3D Event 320A or 320B) or CSAC ( Figures 5A-5B Conditional configuration for events like 568.

[0232] At box 1506, the RAN detects a disconnection from the UE. Figures 3A-3D Events 324-326; Figures 5A-5B Events 524-526). At box 1508, in response to the detection of a disconnection, the RAN suspends communication with the UE via SN radio resources ( Figures 3A-3D Event 328; Figures 5A-5B Incident 528).

[0233] At frame 1510, the RAN identifies the UE on the C-PSCell. Figures 3A-3D Event 336; Figures 5A-5B Event 536). In response to the identification of the UE, at box 1512, the RAN resumes communication with the UE via SN radio resources ( Figures 3A-3D Events 340-342; Figures 5A-5B (Event 542).

[0234] Figure 16 This is a flowchart of an example method for managing communication with the UE after an SCG failure is detected. This method can be implemented in the RAN of this disclosure as a set of instructions stored on a computer-readable medium and executable by, for example, processing hardware (e.g., one or more processors).

[0235] Method 1600 begins at block 1602, in which the RAN communicates with the UE (such as UE 102) via SN radio resources. Figure 3E Event 302; Figure 5C Event 502). Next, at box 1604, the RAN detects a disconnection from the UE ( Figure 3E Events 324-326; Figure 5C Events 524-526). At box 1606, the RAN suspends communication with the UE via SN radio resources in response to detecting a disconnection. Figure 3E Event 328; Figure 5C Incident 528).

[0236] After the pause, at box 1608, the RAN sends the UE information for purposes such as CPAC (…). Figure 3E Event 320A) or CSAC ( Figure 5C Conditional configuration of events such as event 568. At box 1610, the RAN identifies the UE (UE) on the C-PSCell. Figure 3E Event 336; Figure 5C Event 536). Next, at box 1612, the RAN resumes communication with the UE via SN resources ( Figure 3E Events 340-342; Figure 5C (Event 542).

[0237] To further clarify, Figure 17 A flowchart of an example method 1700 for managing mobility is shown, which can be implemented in the UE of this disclosure as a set of instructions stored on a computer-readable medium by processing hardware (e.g., one or more processors). For convenience, method 1700 is discussed below with reference to UE 102.

[0238] Method 1700 begins at block 1702, in which UE 102 operates in DC via PCell and MN and via PSCell and SN. Figures 3A-3G Event 302; Figures 4A-4D Event 402; Figures 5A-5E Event 502; Figure 6A Event 602; Figure 6B Event 603). At box 1704, the UE receives the conditional configuration related to the C-PSCell from the RAN ( Figures 3A-3G , Figures 4A-4D Event 320A or 320B; Figures 5A-5E , Figures 6A-6B Event 568).

[0239] At box 1706, UE 102 detects a communication failure via PSCell or C-PSCell. In some scenarios, detecting a failure may include detecting an SCG failure. Figures 3A-3D Event 322; Figure 3E Event 323; Figure 3F Event 321; Figure 3G Event 325; Figures 5A-5B Event 522; Figure 5C Event 523; Figure 5D Event 521; Figure 5E Event 525). In other scenarios, detecting a failure may include determining that the random access procedure on the C-PSCell has failed ( Figures 4A-4D 444; Figures 6A-6B (644). UE 102 can report communication failures via PSCell or C-PSCell to MN via SCG information failure message. Figures 3A-3G Event 324; Figures 4B-4D Event 494; Figures 5A-5E Event 524; Figure 6B Event 694). UE 102 can indicate in the SCG failure message whether the communication failure is related to PSCell or C-PSCell ( Figure 9 (frame 910).

[0240] Furthermore, in some implementations, UE 102 can detect SCG failure before receiving condition configuration (e.g., Figure 3E , Figure 5C ).

[0241] At box 1708, UE 102 determines the configuration for recovering DC based at least in part on the failure detected at box 1706. For example, UE 102 may retain the conditional configuration in response to detecting an SCG failure. Figures 3A-3D Event 322; Figure 3F Event 321; Figures 5A-5B Event 522; Figure 5E Event 521). If UE 102 has received the conditional configuration, UE 102 may apply the conditional configuration in response to determining that the condition is met or that the C-PSCell is appropriate. Figures 3A-3F Events 334 or 335; Figure 3D Event 354; Figures 4A-4D Event 443; Figures 5A-5C Event 554; Figures 6A-6B Event 643).

[0242] In some implementations, UE 102 may release the conditional configuration in response to detecting an SCG failure. Figure 3G Event 325; Figure 5E Event 525). UE 102 can report SCG failure to MN and subsequently receive configuration from RAN for connecting to SN via a new secondary cell. Figure 3G Event 372; Figure 3E Event 572).

[0243] Furthermore, in some implementations, UE 102 can start a timer in response to detecting an SCG failure and stop the timer in response to connecting to the C-PSCell. If UE 102 does not connect to the C-PSCell before the timer expires, UE 102 can report the SCG failure to the MN (e.g., Figure 3D , Figure 5B ).

[0244] In some implementations, UE 102 may suspend the conditional procedure until the RAN reconfigures the connection with the SN via a new secondary cell (e.g., Figure 3F , Figure 5D ).

[0245] In scenarios where communication with the SN fails due to a failure to connect to the C-PSCell, UE102 can attempt to restore the connection with the SN via the PSCell. Figures 4A-4B Event 445; Figures 6A-6B Event 645). UE 102 can report a failure to MN ( Figures 4B-4D Event 494; Figure 6B Event 694). In some scenarios, UE 102 can retain the conditional configuration and attempt to connect to the C-PSCell after a predetermined amount of time (e.g., Figure 4C In other scenarios, UE 102 can release conditional configurations (e.g., Figure 4D Event 448).

[0246] Figure 18 A flowchart of an example method 1800 for managing communications with a UE (such as UE 102) is shown, which can be implemented in the RAN of this disclosure as a set of instructions stored on a computer-readable medium and executable by, for example, processing hardware (such as one or more processors).

[0247] Method 1800 begins at block 1802, in which the RAN communicates with the UE via the primary cell of the MN and the PSCell of the SN to provide the UE with DC ( Figures 3A-3G Event 302; Figures 4A-4D Event 402; Figures 5A-5E Event 502; Figure 6A Event 602; Figure 6B Event 603). At box 1804, the RAN sends the conditional configuration related to the C-PSCell to the UE ( Figures 3A-3G , Figures 4A-4D Event 320A or 320B; Figures 5A-5E , Figures 6A-6B Event 568). The condition configuration is associated with the conditions that must be met before the UE applies the condition configuration during the condition procedure.

[0248] At box 1806, in response to determining that communication between the UE and the PSCell or C-PSCell has failed, the RAN suspends communication with the UE via the SN. Figures 3A-3G Event 328; Figures 4C-4D Event 428; Figures 5A-5E Event 528). The RAN can receive an indication of SCG failure (e.g., Figures 3A-3F ; Figures 5A-5E ), or by determining that the UE's random access procedure on the C-PSCell has failed (e.g., Figures 4B-4D , Figure 6B This is used to determine if UE communication has failed.

[0249] At box 1808, the RAN resumes communication with the UE via the SN. The RAN can do this via C-PSCell (e.g., Figures 3A-3E , Figures 5A-5C ), new auxiliary cells (e.g., Figures 3F-3G , Figures 5D-5E ) or via PSCell (e.g., Figure 4C Establish a connection between the UE and the SN to restore communication.

[0250] The following description can be applied to the description above.

[0251] The user equipment (e.g., UE 102) that can implement the technologies of this disclosure 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 vehicle's head unit or an advanced driver assistance system (ADAS)). Additionally, 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.

[0252] Some embodiments described in this disclosure include 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 particular manner. A hardware module may include dedicated circuitry or logic that is 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 that is temporarily configured by software to perform certain operations (e.g., contained within a general-purpose processor or other programmable processor). The decision to implement a hardware module in dedicated and permanently configured circuitry or in temporarily configured (e.g., software-configured) circuitry may be driven by cost and time considerations.

[0253] When implemented in software, these technologies can be provided as part of an operating system, a library used by multiple applications, a specific software application, etc. The software can be executed by one or more general-purpose processors or one or more dedicated processors.

[0254] The following list of examples reflects various embodiments explicitly contemplated by this disclosure:

[0255] Example 1. A method for managing mobility in a user equipment (UE) operating in dual connectivity (DC) via a primary cell and a primary node (MN) and via a primary secondary cell and a secondary node (SN), the MN and SN operating in a radio access network (RAN), the method comprising: receiving, by processing hardware, a conditional configuration associated with candidate primary and secondary cells from the RAN, the conditional configuration being associated with conditions to be satisfied by the UE before applying the conditional configuration during a conditional procedure; detecting, by processing hardware, a communication failure via the primary secondary cell or the candidate primary and secondary cell; and determining, by processing hardware, based at least in part on the failure, the configuration under which the UE will resume DC.

[0256] Example 2. According to the method described in Example 1, the detection includes detecting a failure of the secondary cell group (SCG) on the primary and secondary cells.

[0257] Example 3. According to the method described in Example 2, the determination includes: retaining the condition configuration in response to detecting an SCG failure.

[0258] Example 4. According to the method described in Example 3, wherein determining includes: applying condition configuration in response to determining that a condition is met.

[0259] Example 5. According to the method of Example 3, wherein determining includes: when the conditions are not met, applying conditional configuration in response to determining that the candidate secondary cell is suitable.

[0260] Example 6. The method according to any one of Examples 3-5 further includes: reporting SCG failure to MN.

[0261] Example 7. According to the method of Example 6, the method further includes: indicating in the message reporting SCG failure whether the SCG failure is related to the primary / secondary cell or to the candidate primary / secondary cell.

[0262] Example 8. The method according to Example 3 further includes: starting a timer in response to detecting an SCG failure; in a first case: detecting that a condition is met before the timer expires, connecting to a candidate secondary cell and stopping the timer; and in a second case: detecting that the timer expires when the condition is not met; and reporting the SCG failure to the MN.

[0263] Example 9. The method according to Example 3, further comprising: suspending the conditional procedure until the RAN reconfigures its connection with the SN via a new secondary cell.

[0264] Example 10. The method described in Example 2, wherein the detection of SCG failure occurs before the reception condition configuration.

[0265] Example 11. The method according to Example 10, wherein determining includes: applying condition configuration in response to determining that a condition is met.

[0266] Example 12. The method according to Example 10, wherein determining includes: when a condition is not met, applying a conditional configuration in response to determining that a candidate secondary cell is suitable.

[0267] Example 13. The method according to any one of Examples 11-12 further includes: reporting SCG failure to MN.

[0268] Example 14. The method according to Example 13, wherein the report includes: indicating in the message reporting SCG failure whether the SCG failure is related to the primary / secondary cell or to the candidate primary / secondary cell.

[0269] Example 15. The method described in Example 2, wherein determining includes: releasing the conditional configuration in response to SCG failure.

[0270] Example 16. The method according to Example 15, wherein the determination further includes: reporting an SCG failure to the MN; and receiving, after the reporting, configuration from the RAN for connecting to the SN via a new secondary cell.

[0271] Example 17. According to the method of Example 1, the detection includes determining that the random access procedure on the candidate secondary cell has failed.

[0272] Example 18. The method according to Example 17, wherein determining the configuration includes: restoring the connection with the SN via the primary and secondary cells.

[0273] Example 19. The method according to Example 17, wherein determining the configuration includes: reporting an SCG failure to the MN in response to the failure to restore the connection with the SN via the primary and secondary cells.

[0274] Example 20. The method according to Example 17, wherein determining the configuration includes: retaining the conditional configuration after determining that the random access procedure on the candidate secondary cell has failed; and attempting to connect to the candidate secondary cell.

[0275] Example 21. The method according to Example 20, wherein the attempt includes attempting to connect to a candidate secondary cell after a predetermined time period.

[0276] Example 22. The method according to Example 17, wherein determining the configuration includes: releasing the conditional configuration in response to the failure of the random access procedure.

[0277] Example 23. The method according to any of the preceding examples, wherein the conditional procedure is a conditional primary / secondary cell addition or modification (CPAC).

[0278] Example 24. The method according to any of the preceding examples, wherein the conditional procedure is a conditional auxiliary node (SN) addition or modification (CSAC).

[0279] Example 25. A user equipment (UE) includes processing hardware and is configured to implement the method according to any one of Examples 1-24.

[0280] Example 26. A method for configuring a user equipment (UE) in a radio access network (RAN), the method comprising: communicating with the UE via a primary cell of a primary node (MN) and a primary-secondary cell of a secondary node (SN) by processing hardware to provide dual connectivity (DC) to the UE; sending a condition configuration associated with a candidate secondary cell to the UE by the processing hardware, the condition configuration being associated with conditions to be satisfied by the UE before applying the condition configuration during a condition procedure; suspending communication with the UE via the SN in response to determining that communication by the UE via the secondary cell or the candidate secondary cell has failed; and resuming communication with the UE via the SN by the processing hardware.

[0281] Example 27. The method according to Example 26, wherein determining failure includes: receiving an indication of secondary cell group (SCG) failure from the UE.

[0282] Example 28. The method according to Example 26, wherein restoring communication includes establishing a connection between the UE and the SN via a candidate secondary cell.

[0283] Example 29. The method according to Example 26, wherein determining failure includes: determining that the random access procedure of the UE on the candidate secondary cell has failed.

[0284] Example 30. The method according to Example 29, wherein restoring communication includes restoring communication via primary and secondary cells.

[0285] Example 31. The method described in Example 26, wherein the sending occurs before the failure is determined.

[0286] Example 32. The method described in Example 26, wherein the sending occurs after a failure is determined.

[0287] Example 33. The method according to any of the preceding examples, wherein the conditional procedure is a conditional primary / secondary cell addition or modification (CPAC).

[0288] Example 34. The method according to any of the preceding examples, wherein the conditional procedure is a conditional auxiliary node (SN) addition or modification (CSAC).

[0289] Example 35. A base station including processing hardware and configured to implement the method according to any one of Examples 26-34.

Claims

1. A method for managing mobility in a user equipment (UE), the UE operating in dual connectivity (DC) via a primary cell and primary node (MN) associated with a secondary cell group (SCG) and via a primary-secondary cell and secondary node (SN), the MN and SN operating in a radio access network (RAN), the method comprising: The UE receives a condition configuration related to the candidate primary and secondary cell (PSCell) from the RAN. The condition configuration is associated with conditions that must be met before the UE applies the condition configuration during the condition procedure. The UE detected SCG failure; In response to the detection, the UE suspends the conditional procedure. After detecting the SCG failure, a Radio Resource Control (RRC) reconfiguration message for unconditional PSCell change is received from the RAN; and In response to the RRC reconfiguration message, the conditional configuration is released.

2. The method according to claim 1, wherein, The pause includes: The aforementioned conditional configuration is retained.

3. The method according to claim 2, wherein, The pause includes: Stop checking whether the conditions are met.

4. The method according to claim 2, wherein, The pause includes: If the UE detects that the condition is met, it suppresses the application of the condition configuration.

5. The method according to any one of claims 1-4, further comprising: The UE reports the SCG failure to the MN.

6. The method according to claim 5, wherein, The report includes: Send an SCG failure message to the MN.

7. The method according to claim 5, further comprising: The message reporting the SCG failure indicates whether the SCG failure is related to the primary / secondary cell or the candidate primary / secondary cell.

8. The method according to any one of claims 1-4, wherein, The conditional procedure is Conditional Primary / Secondary Cell Change (CPC).

9. The method according to any one of claims 1-4, wherein, The condition procedure is Condition Sub-Node (SN) Addition or Modification (CSAC).

10. The method according to any one of claims 1-4, wherein, Detecting the SCG failure includes detecting at least one of the following: Radio link failure; SCG modification failed; SCG synchronization reconfiguration failed; SCG reconfiguration failed; or Signaling radio bearer 3 (SRB3) integrity failed.

11. A user equipment (UE) including processing hardware and configured to implement the method according to any one of claims 1-10.

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