Patent Publication Number: US-2023143942-A1

Title: Managing a ue preferred configuration

Description:
This disclosure relates generally to wireless communications and, more particularly, to managing a UE preferred configuration. 
     BACKGROUND 
     This background description is provided for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     A user device (or user equipment, commonly denoted by acronym “UE”) in some cases can concurrently utilize resources of multiple network nodes, e.g., base stations, interconnected by a backhaul. These network nodes may support the same RAT or different RATs, and this type of connectivity is generally referred to as DC and specifically MR-DC when different RATs are supported. When a UE operates in DC, one base station operates as a master node (MN), and the other base station operates as a secondary node (SN). The backhaul can support an X2 or Xn interface, for example. 
     The MN can provide a control-plane connection and a user-plane connection to a core network (CN), whereas the SN generally provides a user-plane connection. The cells associated with the MN define a master cell group (MCG), and the cells associated with the SN define a secondary cell group (SCG). The UE and the base stations MN and SN can use signaling radio bearers (SRBs) to exchange radio resource control (RRC) messages, as well as non-access stratum (NAS) messages. 
     There are several types of SRBs that a UE can use when operating in DC. SRB1 and SRB2 resources allow the UE and the MN to exchange RRC messages related to the MN and to embed RRC messages related to the SN, and can be referred to as MCG SRBs. SRB3 resources allow the UE and the SN to exchange RRC messages related to the SN, and can be referred to as an SCG SRB. Split SRBs allow the UE to exchange RRC messages directly with the MN by using radio resources of the MN, the SN, or both of the MN and SN. Further, the UE and the base stations (e.g., MN and SN) use data radio bearers (DRBs) to transport data on a user plane. DRBs terminated at the MN and using the lower-layer resources of only the MN can be referred as MCG DRBs, DRBs terminated at the SN and using the lower-layer resources of only the SN can be referred as SCG DRBs, and DRBs terminated at the MCG but using the lower-layer resources of both the MN and the SN can be referred to as split DRBs. 
     A base station (e.g., MN, SN) and/or the CN in some cases causes the UE to transition from one state of the Radio Resource Control (RRC) protocol to another state. More particularly, the UE can operate in an idle state (e.g., EUTRA-RRC_IDLE, NR-RRC IDLE), in which the UE either does not have a radio connection with a base station or has a suspended RRC connection with the base station; a connected state (e.g., EUTRA-RRC_CONNECTED, NR-RRC_CONNECTED), in which the UE has a radio connection with the base station; or an inactive state (e.g., EUTRA-RRC INACTIVE, NR-RRC INACTIVE), in which the UE has a suspended radio connection with the base station. 
     In some implementations and scenarios, a UE can operate in the connected state and subsequently transition to the inactive state or the idle state. In response to a network-triggering event, such as when a base station pages the UE (e.g., for an incoming phone call), or when the UE is otherwise triggered to send data (e.g., outgoing phone call, browser launch), the UE can then transition back to the connected state. To carry out the transition, the UE can request that the base station resume the suspended radio connection (e.g., by sending an RRC Resume Request message), so that the base station can configure the UE to again operate in the connected state. 
     3GPP TS 36.331 and 38.331 describe procedures for handling UE preferred configurations. These procedures involve a UE sending a preferred configuration in a UEAssistanceInformation message to an MN while in connected state. In transmitting the preferred configuration, the UE is able to suggest to the MN to temporarily adjust the number of SCells, the number of MIMO layers and/or the aggregated bandwidth in use during the connected state when the UE experiences an overheating situation (e.g., due to heavy application processing or high ambient temperature). For example, if the UE and MN are configured to communicate over a maximum number of SCells, a maximum number of MIMO layers, and/or a maximum aggregated bandwidth, the UE can suggest to the MN to reduce the maximum number of SCells, the maximum number of MIMO layers, and/or the maximum aggregated bandwidth, by sending a preferred configuration to the MN that indicates a preferred maximum number of SCells, a preferred maximum number of MIMO layers, and/or a preferred maximum aggregated bandwidth. Thus, a preferred configuration is indicative of a maximum allocation preferred by the UE for one or more resources. 
     However, it is not clear how to handle UE preferred configurations when the UE transitions from the connected state to an inactive state. Further, in scenarios in which the UE is in DC with an MN and an SN, the UE may indicate a preferred maximum number of SCells, a preferred maximum number of MIMO layers, and/or a preferred maximum aggregated bandwidth in a UE preferred configuration for the SN specifically. However, if the SN is a distributed base station that includes a CU and a DU, it is not clear how the CU and the DU handle the UE preferred configuration. Moreover, if the SN does not support the UEAssistanceInformation message, the SN may fail to acknowledge the UE preferred configuration, causing the MN to undesirably revert the UE back to Single Connectivity (SC) with the MN. 
     SUMMARY 
     Base stations and UEs of this disclosure implement techniques that enable a base station and a UE to release or retain, at least temporarily, UE preferred configurations when the UE transitions from the connected state to an inactive state. Further, if the base station is a distributed SN that includes a CU and a DU, the DU can receive the UE preferred configuration via an interface message from the CU. Moreover, in a scenario in which the UE is in DC connectivity with an MN and a legacy SN that does not support the UEAssistanceInformation message to interpret a UE preferred configuration contained in the UEAssistanceInformation message, the MN can translate the UEAssistanceInformation message into a format readable by the SN so that the SN can properly interpret the UE preferred configuration. 
     An example embodiment of these techniques is a method in a UE for managing a preferred configuration indicative of a maximum allocation preferred by the UE for at least one resource. The method is implemented using processing hardware and includes transmitting the preferred configuration to a RAN; transitioning to an inactive state in which a radio connection between the UE and the RAN is suspended; and releasing the preferred configuration, prior to communicating data over the radio connection. 
     Another example embodiment of these techniques is a method in a DU of a disaggregated base station that includes the DU and a central unit CU. The method is implemented using processing hardware and includes receiving, from the CU, a preferred configuration indicative of a maximum allocation preferred by a UE for at least one resource; generating, using the preferred configuration, a DU configuration for the UE; and transmitting, the CU, the DU configuration. 
     Another example embodiment of these techniques is a method in a CU of a disaggregated base station that includes the CU and a DU. The method is implemented using processing hardware and includes receiving a preferred configuration indicative of a maximum allocation preferred by a UE for at least one resource; and transmitting, to the DU, an indication of the maximum allocation preferred by the UE. 
     Yet another example embodiment of these techniques is a method in an MN for managing configuration of an SN when the UE operates in DC with the MN and the SN. The method can be implemented using processing hardware and includes determining, using a capability of at least one of the UE or the SN, whether the SN is to receive an indication of a maximum allocation preferred by the UE for at least one resource; and in response to determining that the SN is to receive the indication, causing the indication to be provided to the SN. 
     Still another example embodiment of these techniques is a method in a UE for managing a preferred configuration indicative of a maximum allocation preferred by the UE for at least one resource, the UE operating in DC with an MN and an SN. The method can be implemented by processing hardware and includes transmitting the preferred configuration to the MN or the SN; receiving an indication that the SN is to be released; disconnecting from the SN in response to the indication; and releasing the preferred configuration. 
     Still another example embodiment of these techniques is a method in a UE for managing a preferred configuration indicative of a maximum allocation preferred by the UE for at least one resource, the UE operating in DC with an MN and a first SN. The method can be implemented by processing hardware and includes transmitting a first preferred configuration to the first SN; receiving, from the MN, mobility information for a secondary cell group (SCG) of a second SN before the first SN successfully receives the first preferred configuration; and determining whether to transmit a second preferred configuration to the first SN or the second SN based on the mobility information. 
     Still another embodiment of these techniques is a base station including processing hardware and configured to implement one of methods above. 
     Another embodiment of these techniques is a UE including processing hardware and configured to implement one of methods above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A and  1 B  are block diagrams of example systems in which a RAN and a UE can implement the techniques of this disclosure for managing UE preferred configurations; 
         FIG.  1 C  is a block diagram of an example base station that can operate in the system of  FIG.  1 A or  1 B ; 
         FIG.  2    is a block diagram of an example protocol stack, according to which the UE of  FIG.  1 A or  1 B  may communicate with the base station(s) of  FIG.  1 A or  1 B ; 
         FIG.  3 A  is a messaging diagram of an example scenario in which the UE releases a preferred configuration after suspending a radio connection with a base station; 
         FIG.  3 B  is a messaging diagram of an example scenario in which the UE retains a preferred configuration after suspending a radio connection with a base station and later overrides the preferred configuration with new preferred configuration upon resuming the radio connection; 
         FIG.  3 C  is a messaging diagram of an example scenario in which the UE releases a preferred configuration prior to suspending a radio connection with a base station; 
         FIG.  4 A  is a messaging diagram of an example scenario in which a central unit (CU) of a disaggregated base station receives a preferred configuration of a UE and transmits the preferred configuration to a distributed unit (DU) of the disaggregated base station; 
         FIG.  4 B  is a messaging diagram of an example scenario in which a CU of a disaggregated base station receives a preferred configuration of a UE and releases the preferred configuration; 
         FIG.  5 A  is a messaging diagram of an example scenario in which the UE provides a preferred configuration to an secondary node (SN) via a master node (MN) and later releases the preferred configuration upon disconnecting from the SN; 
         FIG.  5 B  is a messaging diagram of a scenario similar to the scenario of  FIG.  5 A , but with the SN providing a DU configuration to the UE directly over a radio interface; 
         FIG.  5 C  is a messaging diagram of an example scenario in which an SN initiates an SN release procedure due to the preferred configuration of the UE, and the UE releases the preferred configuration in response to the initiation of the SN release procedure; 
         FIG.  5 D  is a messaging diagram of an example scenario in which the UE retains the preferred configuration in response to the initiation of the SN release procedure, until the UE generates a new preferred configuration; 
         FIG.  5 E  is a messaging diagram of an example scenario in which an SN initiates an SN release procedure due to the preferred configuration of the UE, but the UE retains the preferred configuration in response to the initiation of the SN release procedure, until the UE generates a new preferred configuration; 
         FIG.  5 F  is a messaging diagram of an example scenario in which the MN formats preferred configuration so that the SN can process the preferred configuration; 
         FIG.  5 G  is a messaging diagram of an example scenario in which the MN determines to release an SN in response to receiving a preferred configuration from the SN; 
         FIG.  6 A  is a messaging diagram of an example scenario in which the UE retains a preferred configuration in response to receiving an indication from an MN to suspend a radio connection with the RAN, until the UE generates a new preferred configuration; 
         FIG.  6 B  is a messaging diagram of an example scenario in which the UE releases a preferred configuration after receiving an indication from an MN to suspend a radio connection with an SN; 
         FIG.  6 C  is a messaging diagram of an example scenario in which the UE releases a preferred configuration after receiving an indication from an MN to suspend a radio connection with a legacy SN; 
         FIG.  7    is a messaging diagram of an example scenario in which an MN forwards a preferred configuration from a source SN to a target SN during an SN change procedure; 
         FIG.  8 A  is a flow diagram of an example method that includes releasing a preferred configuration upon suspension of a radio connection, which can be implemented in the UE of  FIGS.  1 A and  1 B ; 
         FIG.  8 B  is a flow diagram of an example method that includes releasing a preferred configuration upon resuming a previously suspended radio connection, which can be implemented in the UE of  FIGS.  1 A and  1 B ; 
         FIG.  9    is a flow diagram of an example method that includes releasing a preferred configuration upon generating a new preferred configuration, which can be implemented in the UE of  FIGS.  1 A and  1 B ; 
         FIG.  10 A  is a flow diagram of an example method that includes releasing a preferred configuration upon disconnecting from an SN, which can be implemented in the UE of  FIGS.  1 A and  1 B ; 
         FIG.  10 B  is a flow diagram of an example method that includes releasing a preferred configuration in response to a configuration of an SN, which can be implemented in the UE of  FIGS.  1 A and  1 B ; 
         FIG.  11    is a flow diagram of an example method that includes releasing a preferred configuration upon generating a new preferred configuration, which can be implemented in the UE of  FIGS.  1 A and  1 B ; 
         FIG.  12 A  is a flow diagram of an example method for determining whether the UE should transmit a preferred configuration to an SN, which can be implemented in an MN of  FIGS.  1 A and  1 B ; 
         FIG.  12 B  is a flow diagram of an example method for determining whether an MN should transmit a preferred configuration to an SN, which can be implemented in an MN of  FIGS.  1 A and  1 B ; 
         FIG.  12 C  is a flow diagram depicting an example method for determining whether to generate a DU configuration using a UE preferred configuration received from an MN, which can be implemented in an SN of  FIGS.  1 A and  1 B ; 
         FIG.  13    is a flow diagram of an example method for processing a UE preferred configuration, which can be implemented in a CU of a disaggregated base station of  FIG.  1 A or  1 B ; 
         FIG.  14 A  is a flow diagram of an example method for analyzing a UE preferred configuration, which can be implemented in an MN of  FIGS.  1 A and  1 B ; 
         FIG.  14 B  is a flow diagram of an example method for analyzing a UE preferred configuration, which can be implemented in an SN of  FIGS.  1 A and  1 B ; 
         FIG.  15    is a flow diagram of an example method for managing a preferred configuration, which can be implemented in a suitable UE. 
         FIG.  16    is a flow diagram of an example method for managing a preferred configuration, which can be implemented in a suitable UE. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG.  1 A  depicts an example wireless communication system  100  that includes a UE  102 , a base station (BS)  104 A, a base station  106 A, and a core network (CN)  110 . The base stations  104 A and  106 A can operate in a RAN  105  connected to the same core network (CN)  110 . The CN  110  can be implemented as an evolved packet core (EPC)  111  or a fifth generation (5G) core (5GC)  160 , for example. 
     Among other components, the EPC  111  can include a Serving Gateway (S-GW)  112  and a Mobility Management Entity (MME)  114 . The S-GW  112  in general is configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., and the MME  114  is configured to manage authentication, registration, paging, and other related functions. The 5GC  160  includes a User Plane Function (UPF)  162  and an Access and Mobility Management (AMF)  164 , and/or Session Management Function (SMF)  166 . Generally speaking, the UPF  162  is configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., the AMF  164  is configured to manage authentication, registration, paging, and other related functions, and the SMF  166  is configured to manage PDU sessions. 
     As illustrated in  FIG.  1 A , the base station  104 A supports a cell  124 A, and the base station  106 A supports a cell  126 A. The cells  124 A and  126 A can partially overlap, so that the UE  102  can communicate in DC with the base station  104 A and the base station  106 A operating as a master node (MN) and a secondary node (SN), respectively. To directly exchange messages during DC scenarios and other scenarios discussed below, the MN  104 A and the SN  106 A can support an X2 or Xn interface. In general, the CN  110  can connect to any suitable number of base stations supporting NR cells and/or EUTRA cells. An example configuration in which the EPC  110  is connected to additional base stations is discussed below with reference to  FIG.  1 B . 
     The base station  104 A is equipped with processing hardware  130  that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. The processing hardware  130  in an example implementation includes an RRC controller  132  configured to manage RRC configurations, such as UE preferred configurations, when the base station  104 A operates as an MN, for example. 
     The base station  106 A is equipped with processing hardware  140  that can also include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. The processing hardware  140  in an example implementation includes an RRC controller  142  configured to manage RRC configurations, such as UE preferred configurations, when the base station  106 A operates as an SN, for example. 
     Still referring to  FIG.  1 A , the UE  102  is equipped with processing hardware  150  that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. The processing hardware  150  in an example implementation includes a UE RRC controller  152  configured to manage RRC configurations, such as UE preferred configurations. 
     More particularly, the RRC controllers  132 ,  142 , and  152  can implement at least some of the techniques discussed with reference to the messaging and flow diagrams below to manage RRC configurations. Although  FIG.  1 A  illustrates the RRC controllers  132  and  142  as separate components, in at least some of the scenarios the base stations  104 A and  106 A can have similar implementations and in different scenarios operate as MN or SN nodes. In these implementations, the base stations  104 A and  106 A can implement the RRC controller  132  and the RRC controller  142  to support MN and SN functionality, respectively. 
     In operation, the UE  102  can use a radio bearer (e.g., a DRB or an SRB) that at different times terminates at the MN  104 A or the SN  106 A. The UE  102  can receive a radio bearer configuration configuring the radio bearer from the MN  104 A or the SN  106 A. The UE  102  can apply one or more security keys when communicating on the radio bearer, in the uplink (from the UE  102  to a base station) and/or downlink (from a base station to the UE  102 ) direction. The UE in some cases can use different RATs to communicate with the base stations  104 A and  106 A. Although the examples below may refer specifically to specific RAT types, 5G NR or EUTRA, in general the techniques of this disclosure also can apply to other suitable radio access and/or core network technologies. 
       FIG.  1 B  depicts another implementation of the example wireless communication system  100  in which communication devices can implement the techniques discussed with reference to the messaging and flow diagrams below to manage RRC configurations. As shown, CN  110  connects to base stations  104 B and  106 B in addition to the base stations  104 A and  106 A. Although not shown to avoid clutter, each of the base stations  104 B and  106 B is equipped with processing hardware that includes an RRC controller similar to the RRC controller  132 A or  142 A. 
     In some implementations and scenarios, the base station  104 A can perform immediate SN addition to configure the UE  102  to operate in dual connectivity (DC) with the base station  104 A (via a PCell) and the base station  106 A (via a PSCell other than cell  126 A). The base stations  104 A and  106 A operate as an MN and an SN for the UE  102 , respectively. The UE  102  in some cases can operate using the MR-DC connectivity mode, e.g., communicate with the base station  104 A using 5G NR and communicate with the base station  106 A using EUTRA, or communicate with the base station  104 A using EUTRA and communicate with the base station  106 A using 5G NR. 
     At some point, the MN  104 A can perform an immediate SN change to change the SN of the UE  102  from the base station  106 A (source SN, or “S-SN”) to the base station  104 B (target SN, or “T-SN”) while the UE  102  is communicating in DC with the MN  104 A and the S-SN  106 A. In another scenario, the SN  106 A can perform an immediate PSCell change to change the PSCell of the UE  102  to the cell  126 A. In one implementation, the SN  106 A can transmit a configuration changing the PSCell to cell  126 A to the UE  102  via a signaling radio bearer (SRB) (e.g., SRB3) for the immediate PSCell change. In another implementation, the SN  106 A can transmit a configuration to the UE  102  via the MN  104 A for the immediate PSCell change to the cell  126 A. The MN  104 A may transmit the configuration immediately changing the PSCell to the cell  126 A to the UE  102  via SRB1. 
     In other scenarios, the base station  104 A can perform a conditional SN Addition procedure to first configure the base station  106 B as a C-SN for the UE  102 , i.e., conditional SN addition or change (CSAC). At this time, the UE  102  can be in SC with the base station  104 A or in DC with the base station  104 A and the base station  106 A. If the UE  102  is in DC with the base station  104 A and the base station  106 A, the MN  104 A may determine to perform the conditional SN Addition procedure in response to a request received from the base station  106 A or in response to one or more measurement results received from the UE  102  or obtained by the MN  104 A from measurements on signals received from the UE  102 . In contrast to the immediate SN Addition case discussed above, the UE  102  does not immediately attempt to connect to the C-SN  106 B. In this scenario, the base station  104 A again operates as an MN, but the base station  106 B initially operates as a C-SN rather than an SN. 
     More particularly, when the UE  102  receives a configuration for the C-SN  106 B, the UE  102  does not connect to the C-SN  106 B until the UE  102  has determined that a certain condition is satisfied (the UE  102  in some cases can consider multiple conditions, but for convenience only the discussion below refers to a single condition). When the UE  102  determines that the condition has been satisfied, the UE  102  connects to the C-SN  106 B, so that the C-SN  106 B begins to operate as the SN  106 B for the UE  102 . Thus, while the base station  106 B operates as a C-SN rather than an SN, the base station  106 B is not yet connected to the UE  102 , and accordingly is not yet servicing the UE  102 . In some implementations, the UE  102  may disconnect from the SN  106 A to connect to the C-SN  106 B. 
     In yet other scenarios, the UE  102  is in DC with the MN  104 A (via a PCell) and SN  106 A (via a PSCell other than cell  126 A and not shown in  FIG.  1 A ). The SN  106 A can perform conditional PSCell addition or change (CPAC) to configure a candidate PSCell (C-PSCell)  126 A for the UE  102 . If the UE  102  is configured a signaling radio bearer (SRB) (e.g., SRB3) to exchange RRC messages with the SN  106 A, the SN  106 A may transmit a configuration for the C-PSCell  126 A to the UE  102  via the SRB, e.g., in response to one or more measurement results which may be received from the UE  102  via the SRB or via the MN  104 A or may be obtained by the SN  106 A from measurements on signals received from the UE  102 . In case of via the MN  104 A, the MN  104 A receives the configuration for the C-PSCell  126 A. In contrast to the immediate PSCell change case discussed above, the UE  102  does not immediately disconnect from the PSCell and attempt to connect to the C-PSCell  126 A. 
     More particularly, when the UE  102  receives a configuration for the C-PSCell  126 A, the UE  102  does not connect to the C-PSCell  126 A until the UE  102  has determined that a certain condition is satisfied (the UE  102  in some cases can consider multiple conditions, but for convenience only the discussion below refers to a single condition). When the UE  102  determines that the condition has been satisfied, the UE  102  connects to the C-PSCell  126 A, so that the C-PSCell  126 A begins to operate as the PSCell  126 A for the UE  102 . Thus, while the cell  126 A operates as a C-PSCell rather than a PSCell, the SN  106 A may not yet connect to the UE  102  via the cell  126 A. In some implementations, the UE  102  may disconnect from the PSCell to connect to the C-PSCell  126 A. 
     In some implementations and scenarios, the condition associated with CSAC or CPAC can be signal strength/quality, which the UE  102  detects on the C-PSCell  126 A of the SN  106 A or on a C-PSCell  126 B of C-SN  106 B, exceeding a certain threshold or otherwise corresponding to an acceptable measurement. For example, when the one or more measurement results the UE  102  obtains on the C-PSCell  126 A are above a threshold configured by the MN  104 A or the SN  106 A or above a pre-determined or pre-configured threshold, the UE  102  determines that the condition is satisfied. When the UE  102  determines that the signal strength/quality on the C-PSCell  126 A of the SN  106 A is sufficiently good (again, measured relative to one or more quantitative thresholds or other quantitative metrics), the UE  102  can perform a random access procedure on the C-PSCell  126 A with the SN  106 A to connect to the SN  106 A. After the UE  102  successfully completes the random access procedure on the C-PSCell  126 A, the C-PSCell  126 A becomes a PSCell  126 A for the UE  102 . The SN  106 A then can start communicating data (user-plane data and/or control-plane data) with the UE  102  via the PSCell  126 A. In another example, when the one or more measurement results the UE  102  obtains on the C-PSCell  126 B are above a threshold configured by the MN  104 A or the C-SN  106 B or above a pre-determined or pre-configured threshold, the UE  102  determines that the condition is satisfied. When the UE  102  determines that the signal strength/quality on the C-PSCell  126 B of the C-SN  106 B is sufficiently good (again, measured relative to one or more quantitative thresholds or other quantitative metrics), the UE  102  can perform a random access procedure on the C-PSCell  126 B with the C-SN  106 B to connect to the C-SN  106 B. After the UE  102  successfully completes the random access procedure on the C-PSCell  126 B, the C-PSCell  126 B becomes a PSCell  126 B for the UE  102  and the C-SN  106 B becomes an SN  106 B. The SN  106 B then can start communicating data (user-plane data and/or control-plane data) with the UE  102  via the PSCell  126 B. 
     In various configurations of the wireless communication system  100 , the base station  104 A can be implemented as a master eNB (MeNB) or a master gNB (MgNB), and the base station  106 A or  106 B can be implemented as a secondary gNB (SgNB) or a candidate SgNB (C-SgNB). The UE  102  can communicate with the base station  104 A and the base station  106 A or  106 B ( 106 A/B) via the same RAT such as EUTRA or NR, or different RATs. When the base station  104 A is an MeNB and the base station  106 A is an SgNB, the UE  102  can be in EUTRA-NR DC (EN-DC) with the MeNB and the SgNB. In this scenario, the MeNB  104 A may or may not configure the base station  106 B as a C-SgNB to the UE  102 . In this scenario, the SgNB  106 A may configure cell  126 A as a C-PSCell to the UE  102 . When the base station  104 A is an MeNB and the base station  106 A is a C-SgNB for the UE  102 , the UE  102  can be in SC with the MeNB. In this scenario, the MeNB  104 A may or may not configure the base station  106 B as another C-SgNB to the UE  102 . 
     In some cases, an MeNB, an SeNB or a C-SgNB is implemented as an ng-eNB rather than an eNB. When the base station  104 A is a Master ng-eNB (Mng-eNB) and the base station  106 A is a SgNB, the UE  102  can be in next generation (NG) EUTRA-NR DC (NGEN-DC) with the Mng-eNB and the SgNB. In this scenario, the MeNB  104 A may or may not configure the base station  106 B as a C-SgNB to the UE  102 . In this scenario, the SgNB  106 A may configure cell  126 A as a C-PSCell to the UE  102 . When the base station  104 A is an Mng-NB and the base station  106 A is a C-SgNB for the UE  102 , the UE  102  can be in SC with the Mng-NB. In this scenario, the Mng-eNB  104 A may or may not configure the base station  106 B as another C-SgNB to the UE  102 . 
     When the base station  104 A is an MgNB and the base station  106 A/B is an SgNB, the UE  102  may be in NR-NR DC (NR-DC) with the MgNB and the SgNB. In this scenario, the MeNB  104 A may or may not configure the base station  106 B as a C-SgNB to the UE  102 . In this scenario, the SgNB  106 A may configure cell  126 A as a C-PSCell to the UE  102 . When the base station  104 A is an MgNB and the base station  106 A is a C-SgNB for the UE  102 , the UE  102  may be in SC with the MgNB. In this scenario, the MgNB  104 A may or may not configure the base station  106 B as another C-SgNB to the UE  102 . 
     When the base station  104 A is an MgNB and the base station  106 A/B is a Secondary ng-eNB (Sng-eNB), the UE  102  may be in NR-EUTRA DC (NE-DC) with the MgNB and the Sng-eNB. In this scenario, the MgNB  104 A may or may not configure the base station  106 B as a C-Sng-eNB to the UE  102 . In this scenario, the Sng-eNB  106 A may configure cell  126 A as a C-PSCell to the UE  102 . When the base station  104 A is an MgNB and the base station  106 A is a candidate Sng-eNB (C-Sng-eNB) for the UE  102 , the UE  102  may be in SC with the MgNB. In this scenario, the MgNB  104 A may or may not configure the base station  106 B as another C-Sng-eNB to the UE  102 . 
     The base stations  104 A,  104 B,  106 A, and  106 B can connect to the same core network (CN)  110  which can be an evolved packet core (EPC)  111  or a fifth-generation core (5GC)  160 . The base station  104 A can be implemented as an eNB supporting an S1 interface for communicating with the EPC  111 , an ng-eNB supporting an NG interface for communicating with the 5GC  160 , or as a base station that supports the NR radio interface as well as an NG interface for communicating with the 5GC  160 . The base station  106 A can be implemented as an EN-DC gNB (en-gNB) with an S1 interface to the EPC  111 , an en-gNB that does not connect to the EPC  111 , a gNB that supports the NR radio interface as well as an NG interface to the 5GC  160 , or a ng-eNB that supports an EUTRA radio interface as well as an NG interface to the 5GC  160 . To directly exchange messages during the scenarios discussed below, the base stations  104 A,  104 B,  106 A, and  106 B can support an X2 or Xn interface. 
     As illustrated in  FIG.  1 B , the base station  104 A supports a cell  124 A, the base station  104 B supports a cell  124 B, the base station  106 A supports a cell  126 A, and the base station  106 B supports a cell  126 B. The cells  124 A and  126 A can partially overlap, as can the cells  124 A and  124 B, so that the UE  102  can communicate in DC with the base station  104 A (operating as an MN) and the base station  106 A (operating as an SN) and, upon completing an SN change, with the base station  104 A (operating as MN) and the SN  104 B. More particularly, when the UE  102  operates in DC with the base station  104 A and the base station  106 A, the base station  104 A operates as an MeNB, an Mng-eNB or an MgNB, and the base station  106 A operates as an SgNB or an Sng-eNB. The cells  124 A and  126 B can partially overlap. When the UE  102  is in SC with the base station  104 A, the base station  104 A operates as an MeNB, an Mng-eNB or an MgNB, and the base station  106 B operates as a C-SgNB or a C-Sng-eNB. When the UE  102  operates in DC with the base station  104 A and the base station  106 A, the base station  104 A operates as an MeNB, an Mng-eNB or an MgNB, the base station  106 A operates as an SgNB or an Sng-eNB, and the base station  106 B operates as a C-SgNB or a C-Sng-eNB. 
     In general, the wireless communication network  100  can include any suitable number of base stations supporting NR cells and/or EUTRA cells. More particularly, the EPC  111  or the 5GC  160  can be connected to any suitable number of base stations supporting NR cells and/or EUTRA cells. Although the examples below refer specifically to specific CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general the techniques of this disclosure also can apply to other suitable radio access and/or core network technologies such as sixth generation (6G) radio access and/or 6G core network or 5G NR-6G DC. 
     In other configurations or scenarios of the wireless communication system  100 , the base station  104 A,  104 B can operate as an MeNB, an Mng-eNB, or an MgNB and the base station  106 A,  106 B can operate as an SgNB or an Sng-eNB. The UE  102  can communicate with the base station  104 A or  104 B and the base station  106 A or  106 B via the same radio access technology (RAT), such as EUTRA or NR, or via different RATs. 
     When the base station  104 A is an MeNB and the base station  106 A is an SgNB, the UE  102  can be in EN-DC with the MeNB  104 A and the SgNB  106 A. When the base station  104 A is an Mng-eNB and the base station  106 A is an SgNB, the UE  102  can be in NGEN-DC with the Mng-eNB  104 A and the SgNB  106 A. When the base station  104 A is an MgNB and the base station  106 A is an SgNB, the UE  102  can be in NR-DC with the MgNB  104 A and the SgNB  106 A. When the base station  104 A is an MgNB and the base station  106 A is an Sng-eNB, the UE  102  can be in NE-DC with the MgNB  104 A and the Sng-eNB  106 A. 
       FIG.  1 C  depicts an example distributed implementation of a base station such as the base station  104 A,  104 B,  106 A, or  106 B. The base station in this implementation can include a centralized unit (CU)  172  and one or more distributed units (DUs)  174 . The CU  172  is equipped with processing hardware that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. In one example, the CU  172  is equipped with the processing hardware  130 . In another example, the CU  172  is equipped with the processing hardware  140 . The processing hardware  140  in an example implementation includes an (C-) SN RRC controller  142  configured to manage or control one or more RRC configurations and/or RRC procedures when the base station  106 A operates as an SN or a candidate SN (C-SN). The base station  106 B can have hardware same as or similar to the base station  106 A. The DU  174  is also equipped with processing hardware that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. In some examples, the processing hardware in an example implementation includes a medium access control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure) and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when the base station  106 A operates as an MN, an SN or a candidate SN (C-SN). The process hardware may include further a physical layer controller configured to manage or control one or more physical layer operations or procedures. 
       FIG.  2    illustrates, in a simplified manner, an example radio protocol stack  200  according to which the UE  102  may communicate with an eNB/ng-eNB or a gNB (e.g., one or more of the base stations  104 A,  104 B,  106 A,  106 B). In the example stack  200 , a physical layer (PHY)  202 A of EUTRA provides transport channels to the EUTRA MAC sublayer  204 A, which in turn provides logical channels to the EUTRA RLC sublayer  206 A. The EUTRA RLC sublayer  206 A in turn provides RLC channels to the EUTRA PDCP sublayer  208  and, in some cases, to the NR PDCP sublayer  210 . Similarly, the NR PHY  202 B provides transport channels to the NR MAC sublayer  204 B, which in turn provides logical channels to the NR RLC sublayer  206 B. The NR RLC sublayer  206 B in turn provides RLC channels to the NR PDCP sublayer  210 . The UE  102 , in some implementations, supports both the EUTRA and the NR stack as shown in  FIG.  2   , to support handover between EUTRA and NR base stations and/or to support DC over EUTRA and NR interfaces. Further, as illustrated in  FIG.  2   , the UE  102  can support layering of NR PDCP sublayer  210  over the EUTRA RLC sublayer  206 A. 
     The EUTRA PDCP sublayer  208  and the NR PDCP sublayer  210  receive packets (e.g., from an Internet Protocol (IP) layer, layered directly or indirectly over the PDCP layer  208  or  210 ) that can be referred to as service data units (SDUs), and output packets (e.g., to the RLC layer  206 A or  206 B) that can be referred to as protocol data units (PDUs). Except where the difference between SDUs and PDUs is relevant, this disclosure for simplicity refers to both SDUs and PDUs as “packets.” 
     On a control plane, the EUTRA PDCP sublayer  208  and the NR PDCP sublayer  210  can provide SRBs to exchange RRC messages, for example. On a user plane, the EUTRA PDCP sublayer  208  and the NR PDCP sublayer  210  can provide DRBs to support data exchange. 
     In scenarios where the UE  102  operates in EUTRA/NR DC (EN-DC), with the base station  104 A operating as an MeNB and the base station  106 A operating as an SgNB, the wireless communication system  100  can provide the UE  102  with an MN-terminated bearer that uses the EUTRA PDCP sublayer  208 , or an MN-terminated bearer that uses the NR PDCP sublayer  210 . The wireless communication system  100  in various scenarios can also provide the UE  102  with an SN-terminated bearer, which uses only the NR PDCP sublayer  210 . The MN-terminated bearer can be an MCG bearer, a SCG bearer, or a split bearer. The SN-terminated bearer can be, an MCG bearer, an SCG bearer or a split bearer. The MN-terminated bearer can be an SRB (e.g., SRB1 or SRB2) or a DRB. The SN-terminated bearer can an SRB or a DRB. 
     Next, several example scenarios in which a UE  102  and/or a RAN  105  manage a UE preferred configuration (or interchangeably referred herein as simply “preferred configuration”) are discussed with reference to  FIGS.  3 A- 14 B . Generally, in these scenarios, the UE  102  can transmit one or more preferred configurations (i.e., a first preferred configuration, a second preferred configuration, as will be further described below) in a UEAssistanceInformation message to a base station (e.g., base station  104 A, base station  104 B, base station  106 A) of the RAN  105  to suggest temporarily adjusting the number of SCells, the number of MIMO layers, the aggregated bandwidth for UL and/or DL, and/or other suitable configuration parameters that are in use when communicating with the UE  102 . As such, in some implementations, the preferred configuration indicates a maximum number of SCells, a maximum number of MIMO layers, and/or a maximum aggregated bandwidth for uplink and downlink communications that are preferred by the UE  102 . As used herein, the “number of SCells” may include a PSCell, or alternatively exclude the PSCell. In some implementations, the preferred configuration includes a discontinuous reception (DRX) configuration. The DRX configuration can include a DRX cycle and an on duration (or off duration). In yet other implementations, the preferred configuration includes indications for enabling/disabling 5G, enabling/disabling DC, or enabling/disabling power saving. In other implementations, the preferred configuration includes configured grant assistance information for V2X sidelink communication (e.g., sl-UE-AssistanceInformationNR), minimum scheduling offset for cross-slot scheduling (e.g., minSchedulingOffsetPreference), and/or an indication of interest in reference time information (e.g., reference TimeInfoInterest). In some implementations, the UE assistance information message can be an existing RRC message such as a UEAssistanceInformation message or a newly defined RRC message. In other implementations, the UE assistance information message can be an RRC response message in response to the RRC message enabling the UE  102  to transmit a preferred configuration. In yet other implementations, the UE  102  can indicate to release a first preferred configuration in a second preferred configuration or a UE assistance information message. In yet other implementations, the UE  102  can indicate to release some parameters contained within a first preferred configuration in a second preferred configuration or a UE assistance information message. 
     Now referring to  FIGS.  3 A- 3 C , in various scenarios, the UE  102  can release a preferred configuration prior to suspending a radio connection with a base station, or retain a preferred configuration after suspending a radio connection with a base station (and later override the preferred configuration with new preferred configuration upon resuming the radio connection). The UE  102  can be in SC with the base station, or in DC with the base station and another base station. The base station can be an aggregated base station or a distributed base station that includes a central unit (CU) and a distributed unit (DU). 
     Referring first to  FIG.  3 A , in a scenario  300 A, the base station  104 A operates as a serving base station for UE  102 . In some implementations, the base station  104 A is a distributed base station that includes a central unit (CU)  172  and a distributed unit (DU)  174 , as shown in  FIG.  3 A . In other implementations, the base station  104 A is an aggregated base station (i.e., not split into a CU and a DU). 
     Initially, the UE  102  operates in a connected state (e.g., RRC_CONNECTED) and communicates  302 A data (e.g., uplink (UL) PDUs and/or downlink (DL) PDUs) in SC with the CU  172  and the DU  174  via cell  124 A by using a BS configuration which includes multiple configurations, each corresponding to a respective configuration parameter. The configuration parameters specify the SCell(s), MIMO layers, aggregated bandwidth, discontinuous reception (DRX) configuration, etc. configured to the UE  102  in the BS configuration. In other implementations and scenarios, although not shown in  FIG.  3 A , the UE  102  can communicate  302 A data in DC with the base station  104 A operating as an MN and an SN (e.g., the base station  106 A), or in DC with the CU  172 , the DU  174 , and a secondary DU. In some implementations, during event  302 A, the CU  172  can receive UE capabilities of the UE  102  from the UE  102 , the CN  110  (e.g., an MME  114  or AMF  164 ), or another base station (e.g., base station  104 B), and forward the UE capabilities to the DU  174 . In turn, the DU  174  can establish the multiple configuration parameters according to the UE capabilities. In some implementations, the CU  172  can receive the UE capabilities in an information element (IE) (e.g., a UE-EUTRA-Capability IE, a UE-NR-Capability IE, a UE-MRDC-Capability IE) or in a UE capability information message that includes the IE, and forward the IE or UE capability information message to the DU  174 . 
     Later in time, the CU  172  performs  304 A a UE assistance configuration procedure with the UE  102  via the DU  174  to enable (i.e., permit or allow) the UE  102  to transmit a preferred configuration to the base station  104 A. During the UE assistance configuration procedure, the CU  172  can transmit an RRC message (e.g., an RRC reconfiguration message or a newly defined RRC message) to the UE  102  via the DU  174  to enable the UE  102  to transmit a preferred configuration, and in turn, the UE  102  can transmit an RRC response message (e.g., an RRC reconfiguration complete message or a newly defined RRC response message) to the CU  172  via the DU  174 , in some implementations. The CU  172  can include a field or IE (e.g., a newly defined field/IE or an existing field/IE in 3GPP specification 36.331 or 38.331) in the RRC message to enable the UE  102  to transmit a preferred configuration. For example, the CU  172  can include an OtherConfig IE, an overheating configuration (e.g., OverheatingAssistance IE or overheatingAssistanceConfig field), a power saving configuration (e.g., PowerPrefindicationConfig IE), or the OtherConfig IE that includes the OverheatingAssistanceConfig IE, the overheatingAssistanceConfig field, and/or the PowerPrefindicationConfig IE in the RRC message to enable the UE  102  to provide the preferred configuration. In another example, the CU  172  can include a reference time interest reporting (e.g., reference TimeInterestReporting-r16), a sidelink configuration (e.g., sl-AssistanceConfigNR-r16), an in-device coexistence (IDC) configuration (e.g., idc-AssistanceConfig), a Bluetooth configuration (e.g., btNameList-r16), a wireless local area network (WLAN) configuration (e.g., wlanNameList-r16), a sensor configuration (e.g., sensorNameList-r16), a location configuration (e.g., obtainCommonLocationConfig-r16), and/or at least one power saving configuration (e.g., drx-PreferenceConfig-r16, maxBW-PreferenceConfig-r16, maxCC-PreferenceConfig-r16, maxMIMO-LayerPreferenceConfig-r16, minSchedulingOffsetPreferenceConfig-r16, releasePreferenceConfig-r16) in the RRC message to enable the UE  102  to provide the preferred configuration. In other implementations, during the UE assistance configuration procedure, the CU  172  can broadcast an RRC message (e.g., system information block) via PCell  124 A to enable the UE  102  to transmit the preferred configuration. 
     After the UE  102  is enabled to transmit a preferred configuration, the UE  102  transmits  306 A a UE assistance information message including the preferred configuration (i.e., a first preferred configuration) to the DU  174 . The DU  174  in turn sends  308 A the UE assistance information message to the CU  172 . The events  306 A and  308 A are collectively referred to in  FIG.  3 A  as a UE assistance information procedure  372 A. 
     The UE  102  can transmit  306 A the first preferred configuration for different reasons in various scenarios and implementations. In one implementation, the UE  102  can transmit the first preferred configuration if the UE  102  is not satisfied with configuration parameters in the BS configuration that are used by the UE  102  to communicate with the base station  104 A, as described in event  302 A (i.e., the configuration parameters do not satisfy the preferences of the UE  102  as defined in the first preferred configuration). In another implementation, the UE  102  can transmit the first preferred configuration even if the UE  102  is satisfied with the configuration parameters, to prevent the base station  104 A from changing the configuration parameters to ones that the UE  102  may not prefer. In another implementation, the UE  102  can transmit the first preferred configuration if the UE  102  experiences an overheating situation (e.g., due to heavy application processing), detects low battery power, or otherwise determines to conserve power, e.g., in response to the overheating configuration received in the RRC message from the base station  104 A. In this way, the UE  102  can transmit the first preferred configuration for power saving purposes (even if the UE  102  does not experience an overheating situation), overheating purposes, or both. 
     In response to receiving  308 A the UE assistance information message from the DU  174 , the CU  172  sends  310 A a first interface message (e.g., UE Context Modification Request message, UE Context Setup Request message) including the first preferred configuration to the DU  174 . In some implementations, the DU  174  generates  312 A a DU configuration for the UE  102  in response to the first preferred configuration if the configuration parameters in the BS configuration do not satisfy the first preferred configuration, or if the DU  174  determines to modify the configuration parameters despite the configuration parameters satisfying the first preferred configuration. The DU  174  generates the DU configuration in a manner that would not exceed the capabilities of the UE  102 , e.g., by considering the UE capabilities included in the first interface message received from the CU  172  at event  310 A. 
     In some scenarios and implementations, the UE  102  can send the first preferred configuration to the base station  104 A to request that the base station  104 A generate a DU configuration that would not maximize capabilities of the UE  102  as defined in the UE capabilities. For example, in response to receiving the first preferred configuration from the UE  102  that indicates a preferred maximum number of SCell(s), a preferred maximum number of MIMO layer(s), and/or maximum aggregated bandwidth that is less than the corresponding maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth supported by the UE capabilities, the base station  104 A can generate a DU configuration that indicates no more than the preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth indicated in the first preferred configuration. Effectively, the DU configuration can be generated by the base station  104 A (e.g., the DU  174  of the base station  104 A) for the UE  102  to release some of the SCell(s), MIMO layer(s), and/or aggregated bandwidth that were indicated in the BS configuration mentioned above with respect to event  302 A, to ensure that the UE  102  communicates with the DU  174  via the preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth or less as indicated in the first preferred configuration. 
     After the DU  174  generates the DU configuration at event  312 A, the DU  174  can then send  314 A a second interface message (e.g., UE Context Modification Response message, UE Context Modification Required message, UE Context Setup Response message) including the DU configuration to the CU  172 . In other implementations, in response to receiving  310 A the first preferred configuration, the DU  174  need not generate the DU configuration if the configuration parameters in the BS configuration satisfy the first preferred configuration. In this case, the DU  174  may omit the DU configuration in the second interface message, or may include a DU configuration irrelevant to the first preferred configuration in the second interface message. In response to receiving the second interface message from the DU  174 , the CU  172  can send a UE Context Modification Confirm message to the DU  174 . The events  310 A,  312 A, and  314 A are collectively referred to in  FIG.  3 A  as a DU reconfiguration procedure  374 A. 
     In some implementations, after receiving the DU configuration from the DU  174 , the CU  172  sends  316 A an RRC reconfiguration message including the DU configuration to the DU  174 , which in turn transmits  318 A the RRC reconfiguration message to the UE  102 . In response, the UE  102  can transmit  320 A an RRC reconfiguration complete message to the DU  174 , which in turn sends  322 A the RRC reconfiguration complete message to the CU  172 . By receiving the DU configuration, the UE  102  can update the multiple configuration parameters previously provided by the base station  104 A at event  302 A with the DU configuration, and communicate with the DU  174  by using the updated configuration parameters. In some implementations, the CU  172  can send  316 A a DL RRC Message Transfer message including the RRC reconfiguration message to the DU  174 , which in turn can send  322 A a UL RRC Message Transfer message including the RRC reconfiguration complete message to the CU  172 . The events  316 A,  318 A,  320 A, and  322 A are collectively referred to in  FIG.  3 A  as an RRC reconfiguration procedure  376 A. 
     Although the DU  174  is described as generating one DU configuration at step  312 A, the DU  174  may generate multiple DU configurations. If the DU  174  generates multiple DU configurations, the CU  172  and the UE  102  can perform the RRC reconfiguration procedure  376 A multiple times so that the UE  102  can obtain the multiple DU configurations. 
     In some scenarios and implementations, after receiving the first preferred configuration at event  372 A, the CU  172  may perform a DU reconfiguration procedure with a candidate DU (C-DU) which can be e.g., the DU  174  or a DU not shown in  FIG.  3 A , similar to the DU reconfiguration procedure  374 A, to prepare a conditional configuration for conditional handover (CHO) for the UE  102 . In the DU reconfiguration procedure, the CU  172  can send a first interface message, similar to event  310 A, to the C-DU to obtain a C-DU configuration generated by the C-DU that satisfies the first preferred configuration. In other scenarios and implementations, either before or after event  372 A, the CU  172  may perform a DU reconfiguration procedure with a C-DU which can be e.g., the DU  174  or a DU not shown in  FIG.  3 A , similar to the DU reconfiguration procedure  374 A, to prepare a conditional configuration for CHO for the UE  102 . In the DU reconfiguration procedure, the CU  172  can send a first interface message, similar to event  310 A, but exclude the first preferred configuration, to the C-DU to obtain a C-DU configuration generated by the C-DU according to the UE capabilities stored in the C-DU or included in the first interface message. 
     In any event, after the CU  172  obtains the C-DU configuration, the CU  172  generates an RRC message including the C-DU configuration, a conditional configuration including the RRC message, and an RRC reconfiguration message including the conditional configuration. Then the CU  172  transmits the RRC reconfiguration message to the UE  102  via the DU  174 . The UE  102  can transmit an RRC reconfiguration complete message to the CU  172  via the DU  174  in response. Later, if the UE  102  detects that a condition for connecting to a candidate cell is satisfied, the UE  102  connects to the C-DU via the candidate cell. The CU  172  can perform a DU reconfiguration procedure and an RRC reconfiguration procedure with the UE  102  and C-DU to transmit another DU configuration satisfying the first preferred configuration to the UE  102 , similar to the DU reconfiguration procedure  374 A and RRC reconfiguration procedure  376 A. 
     If the CU  172  transmits a conditional configuration (i.e., a first conditional configuration) to the UE  102  before receiving the first preferred configuration from the UE  102 , the CU  172  may not update the conditional configuration even though the conditional configuration does not satisfy the first preferred configuration, in one implementation. In another implementation, if the conditional configuration does not satisfy the first preferred configuration, the CU  172  can transmit an RRC reconfiguration message releasing the conditional configuration to the UE  102 . In yet another implementation, the CU  172  can transmit an RRC reconfiguration message to the UE  102  for releasing the conditional configuration in response to receiving the first preferred configuration from the UE  102 . In yet another implementation, if the conditional configuration does not satisfy the first preferred configuration received from the UE  102 , the CU  172  can transmit an RRC reconfiguration message including another conditional configuration (i.e., a second conditional configuration) to the UE  102  to replace the first conditional configuration. The CU  172  can perform a DU reconfiguration procedure with the C-DU to obtain a new C-DU configuration satisfying the first preferred configuration and transmit the second conditional configuration including the new C-DU configuration to the UE  102  in a similar manner as described above. 
     In some scenarios and implementations, after receiving the first preferred configuration at event  372 A, the CU  172  may perform a handover preparation procedure with a candidate base station (C-BS) (e.g., base station  106 B not shown in  FIG.  3 A ), to prepare a conditional configuration for CHO for the UE  102 . In the handover preparation reconfiguration procedure, the CU  172  can send a Handover Request message (i.e., a CHO command) to the C-BS to obtain a C-BS configuration. The C-BS can generate a C-BS configuration satisfying the first preferred configuration and send a Handover Request Acknowledge message including the C-BS configuration to the CU  172  in response to the Handover Request message. In other scenarios and implementations, either before or after event  372 A, the CU  172  may perform a handover preparation procedure with a C-BS (e.g., base station  106 B not shown in  FIG.  3 A ), to prepare a conditional configuration for CHO for the UE  102 . In the handover preparation reconfiguration procedure, the CU  172  can send a Handover Request message excluding the first preferred configuration to the C-BS to obtain a C-BS configuration. The C-BS can generate a C-BS configuration according to the UE capabilities included in the Handover Request message and send a Handover Request Acknowledge message including the C-BS configuration to the CU  172  in response to the Handover Request message. 
     In any event, after the CU  172  obtains the C-BS configuration, the CU  172  generates a conditional configuration including the C-BS configuration and an RRC reconfiguration message including the conditional configuration. Then the CU  172  transmits the RRC reconfiguration message to the UE  102  via the DU  174 . The UE  102  can transmit an RRC reconfiguration complete message to the CU  172  via the DU  174  in response. Later, if the UE  102  detects that a condition for connecting to a candidate cell is satisfied, the UE  102  connects to the C-B S via the candidate cell. If the C-B S receives the first preferred configuration from the UE  102  or the CU  172 , the C-BS can perform a DU reconfiguration procedure and an RRC reconfiguration procedure with the UE  102  and C-DU to transmit another DU configuration satisfying the first preferred configuration to the UE  102 , similar to the DU reconfiguration procedure  374 A and RRC reconfiguration procedure  376 A. 
     If the CU  172  transmits a conditional configuration (i.e., a first conditional configuration) to the UE  102  before receiving the first preferred configuration from the UE  102 , the CU  172  may not update the conditional configuration even though the conditional configuration does not satisfy the first preferred configuration, in one implementation. In another implementation, if the conditional configuration does not satisfy the first preferred configuration, the CU  172  can transmit to the UE  102  an RRC reconfiguration message for releasing the conditional configuration. In yet another implementation, the CU  172  can transmit an RRC reconfiguration message to the UE  102  for releasing the conditional configuration in response to receiving the first preferred configuration from the UE  102 . In yet another implementation, if the conditional configuration does not satisfy the first preferred configuration received from the UE  102 , the CU  172  can transmit an RRC reconfiguration message including another conditional configuration (i.e., a second conditional configuration) to the UE  102  to replace the first conditional configuration. The CU  172  can perform a DU reconfiguration procedure with the C-DU to obtain a new C-DU configuration satisfying the first preferred configuration and transmit the second conditional configuration including the new C-DU configuration to the UE  102  in a similar manner as described above. 
     Later in time (e.g., after the CU  172  detects that traffic of the UE  102  is inactive on the BS-terminated radio bearer(s)), the CU  172  determines to suspend a radio connection (e.g., including an RRC connection) with the UE  102 . The CU  172  then sends  324 A an RRC suspension message (e.g., an RRCRelease message, an RRCConnectionRelease message) to the DU  174 , which in turn transmits  326 A the RRC suspension message to the UE  102 . As a result, the UE  102  suspends  328 A the radio connection, and can transition to an inactive state or an idle state. In some implementations, the CU  172  can send  324 A a UE Context Release Command message including the RRC suspension message to the DU  174 , which in turn can send a UE Context Release Complete message to the CU  172  in response. The RRC suspension message can include a SuspendConfig IE, an RRC-InactiveConfig-r15 IE, or a ResumeIdentity-r13 IE. The events  324 A,  326 A, and  328 A are collectively referred to in  FIG.  3 A  as an RRC suspension procedure  378 A. 
     As discussed above, in some implementations, in response to receiving  310 A the first preferred configuration, the DU  174  need not generate the DU configuration if the configuration parameters in the BS configuration satisfy the first preferred configuration. In these implementations, the base station  104 A need not perform the DU reconfiguration procedure  374 A and the RRC reconfiguration procedure  376 A before the RRC suspension procedure  378 A. The base station  104 A may not perform the DU reconfiguration procedure  374 A and the RRC reconfiguration procedure  376 A for other reasons, such as when the CU  172  is transmitting a high volume of data to the UE  102 , or is otherwise busy, for example. 
     Later in time after suspending  328 A the radio connection, the UE  102  can perform an RRC resume procedure  380 A to transition from the inactive or idle state to the connected state, e.g., in response to determining to initiate a data transmission with the base station  104 A, or in response to a Paging message received from the base station  104 A. In the RRC resume procedure  380 A, the UE  102  transmits  330 A an RRC resume request message to the DU  174 , which in turn sends  332 A the RRC resume request message to the CU  172 . In response, the CU  172  sends  334 A an RRC resume message to the DU  174 , which in turn transmits  336 A the RRC resume message to the UE  102 . As a result, the UE  102  resumes  338 A the suspended radio connection in response to the RRC resume message and transitions to the connected state. The UE  102  can transmit  340 A an RRC resume complete message to the DU  174 , which in turn can send  342 A the RRC resume complete message to the CU  172 . Although the UE  102  is described as performing the RRC resume procedure  380 A with the DU  174 , in other implementations, the UE  102  can perform the RRC resume procedure  380 A with another DU (i.e., different than DU  174 ) connected to the CU  172 . 
     In some implementations, after the base station  104 A performs the RRC suspension procedure  378 A with the UE  102 , the UE  102  can release  352 A the first preferred configuration (e.g., in response to receiving  326 A the RRC suspension message). Similarly, in some implementations, the CU  172  can release  351 A the first preferred configuration in response to determining to suspend the radio connection with the UE  102 . In other implementations, the UE  102  can release  352 A the first preferred configuration in response to initiating the RRC resume procedure  380 A (e.g., transmitting  330 A the RRC resume request message), during the RRC resume procedure  380 A (e.g., in response to receiving  336 A the RRC resume message), or after transmitting  340 A the RRC resume complete message. Similarly, in some implementations, the CU  172  can release  351 A the first preferred configuration during the RRC resume procedure  380 A (e.g., in response to receiving  332 A the RRC resume request message, transmitting  334 A the RRC resume message), or after receiving  342 A the RRC resume complete message. 
     By releasing the first preferred configuration at the UE  102  and the CU  172 , the UE  102  and the CU  172  need not be limited to communicating with each other according to the first preferred configuration upon resuming the suspended radio connection. For example, the UE  102  may have recovered from an overheating situation or increased battery power since the inactive state or an idle state, such that the UE  102  is able to utilize more SCell(s), MIMO layer(s), and/or aggregated bandwidth than those indicated in the first preferred configuration after transitioning back to the connected state. Because the UE  102  and the CU  172  are still aware of the BS configuration (including the updated configuration parameters configured by the RRC reconfiguration procedure  376 A), the UE  102  and the CU  172  may proceed to communicate using the BS configuration again, for example. 
     In some implementations, in addition to releasing the first preferred configuration, the UE  102  can either release or retain some or all configurations in the BS configuration in response to receiving  326 A the RRC suspension message (i.e., while the UE  102  is in inactive state or idle state). Similarly, in addition to releasing the first preferred configuration, the CU  172  can also either release or retain some or all configurations in the BS configuration while the UE  102  is in inactive state or idle state. In some implementations, the UE  102  can release or update the retained configuration(s) in the BS configuration if the UE  102  receives configuration(s) in the RRC resume message from the base station  104 A at event  336 A. In one such implementation, the CU  172  can obtain another DU configuration (i.e., second DU configuration) from the DU  174 , e.g., by using a UE Context Setup procedure (e.g., as will be described in  FIG.  4 A  below), and include the second DU configuration in the RRC resume message. In another such implementation, the CU  172  can generate configuration(s) and include the generated configuration(s) in the RRC resume message. In other implementations, after receiving the RRC resume complete message, the CU  172  can obtain another DU configuration (i.e., second DU configuration) from the DU  174 , e.g., by using a DU reconfiguration procedure similar to the DU reconfiguration procedure  374 A and perform an RRC reconfiguration procedure with the UE  102 , similar to the RRC reconfiguration procedure  376 A. The CU  172  can include the second DU configuration in an RRC reconfiguration message in the RRC reconfiguration procedure. Because the CU  172  releases the first preferred configuration at event  351 A, the CU  172  does not send the first preferred configuration to the DU  174  during the DU reconfiguration procedure or the UE Context Setup procedure (see  FIG.  4 A ). Therefore, the DU  174  generates the second DU configuration in a manner that would not underestimate the capabilities of the UE  102 , e.g., by considering the UE capabilities rather than the first preferred configuration. 
     In some implementations, while the UE  102  is in inactive state or idle state, the UE  102  can retain the current security keys (e.g., K gNB  and K RRCint  keys), a Robust Header Compression (ROHC) state if ROHC is configured at the UE  102 , QoS flow to DRB mapping rules, a Cell Radio Network Temporary Identifier (C-RNTI) used in a source PCell (e.g., PCell  124 A), a cell identity (cellIdentity) and a physical cell identity of the source PCell, and other configuration parameters in a radio link control (RLC) configuration (e.g., RLCBearerConfig IE(s)), a medium access control (MAC) configuration (e.g., MAC-CellGroupConfig IE(s)) and/or a physical layer configuration (e.g., PhysicalCellGroupConfig IE(s)). In some implementations, while the UE  102  is in inactive state or idle state, the UE  102  can retain the field or IE that enables the UE  102  to transmit the first preferred configuration. In other implementations, the UE  102  can release configurations within ReconfigurationWithSync IE and/or ServingCellConfigCommonSlB IE and/or the field or IE that enables the UE  102  to transmit the first preferred configuration in response to the RRC suspension message in the RRC suspension procedure  378 A or during the RRC resume procedure  380 A. 
     In some implementations, after the base station  104 A performs the RRC suspension procedure  378 A with the UE  102 , the UE  102  can release the OtherConfig IE, the overheating configuration, and/or the power saving configuration (e.g., in response to receiving  326 A the RRC suspension message). Similarly, in some implementations, the CU  172  can release the OtherConfig IE, the overheating configuration, and/or the power saving configuration in response to determining to suspend the radio connection with the UE  102 . In other implementations, the UE  102  can release the OtherConfig IE, the overheating configuration, and/or the power saving configuration in response to initiating the RRC resume procedure  380 A (e.g., transmitting  330 A the RRC resume request message), during the RRC resume procedure  380 A (e.g., in response to receiving  336 A the RRC resume message), or after transmitting  340 A the RRC resume complete message. Similarly, in some implementations, the CU  172  can release the OtherConfig IE, the overheating configuration, and/or the power saving configuration during the RRC resume procedure  380 A (e.g., in response to receiving  332 A the RRC resume request message, transmitting  334 A the RRC resume message), or after receiving  342 A the RRC resume complete message. The UE  102  can disable transmission of a UE assistance information message in response to releasing the OtherConfig IE, the overheating configuration, and/or the power saving configuration. 
     In the first preferred configuration or UE assistance information message, the UE  102  can include reducedCCsDL field to indicate a preferred maximum number of SCell(s). The UE  102  may or may not include the reducedCCsUL field in the first preferred configuration or UE assistance information message. If the CU  172  or the DU  174  receives the reducedCCsDL field with value X and the reducedCCsUL field with value Y, and X is smaller than Y, the CU  172  or the DU  174  can ignore the reducedCCsUL field. 
     In some implementations, the DU configuration described above includes at least one of physical configuration(s), medium access control (MAC) configuration(s), and radio link configuration(s). The DU configuration may not include a radio bearer configuration. For example, the DU configuration can be a CellGroupConfig IE, a RadioResourceConfigDedicated IE, a RRCConnectionReconfiguration-r8-IEs IE or a RRCReconfiguration-IEs IE. 
     In some implementations, the BS configuration described above can be an RRCReconfiguration message, RRCReconfiguration-IEs, or the CellGroupConfig IE conforming to 3GPP TS 38.331, or an RRCConnectionReconfiguration message or RRCConnectionReconfiguration-IEs conforming to 3GPP TS 36.331. In other implementations, the BS configuration can include configurations in the CellGroupConfig IE, RRCReconfiguration-IEs, or RRCConnectionReconfiguration-IEs. In yet other implementations, the BS configuration can include configurations in a ServingCellConfigCommonSlB IE. In further implementations, the BS configuration can also include radio bearer configuration(s) (RadioBearerConfig IE, DRB-ToAddMod IEs and/or SRB-ToAddMod IEs) and/or a measurement configuration (MeasConfig IE). 
     In some implementations, if the base station  104 A is a gNB, the RRC reconfiguration message and the RRC reconfiguration complete message can be an RRCReconfiguration message and an RRCReconfigurationComplete message, respectively. In other implementations, if the base station  104 A is an eNB or an ng-eNB, the RRC reconfiguration message and the RRC reconfiguration complete message can be an RRCConnectionReconfiguration message and an RRCConnectionReconfigurationComplete message, respectively. 
     In some implementations, if the base station  104 A is a gNB, the RRC resume request message, the RRC resume message, and the RRC resume complete message can be an RRCResumeRequest message, an RRCResume message, and an RRCResumeComplete message, respectively. In other implementations, if the base station  104 A is an eNB or an ng-eNB, the RRC resume request message, the RRC resume message, and the RRC resume complete message can be an RRCConnectionResumeReuquest message, an RRCConnectionResume message, and an RRCConnectionResumeComplete message, respectively. 
     Referring now to  FIG.  3 B , in a scenario  300 B, the base station  104 A again operates as a serving base station for UE  102 , similar to scenario  300 A. Whereas in  FIG.  3 A  the UE  102  and the CU  172  releases the first preferred configuration to revert back to using the BS configuration upon resuming communication with each other, in  FIG.  3 B  the UE  102  and the base station  104 A retain the first preferred configuration, and later the UE  102  provides a second preferred configuration to override the retained first preferred configuration upon resuming connectivity with the CU  172 . The UE  102  thus initially retains the first preferred configuration but nevertheless releases the first preferred configuration prior to communicating data with the RAN  105  over the radio connection. 
     Generally, the CU  172  and DU  174  in  FIG.  3 B  can perform similar actions as the CU  172  and DU  174  in  FIG.  3 A , respectively. 
     Initially, the UE  102  operates in a connected state and communicates  302 B data with the CU  172  and the DU  174  via cell  124 A by using a BS configuration, which includes multiple configurations, each corresponding to a respective configuration parameter, similar to event  302 A. 
     Later in time, the CU  172  performs  304 B a UE assistance configuration procedure with the UE  102  via the DU  174  to enable the UE  102  to transmit a preferred configuration to the base station  104 A, similar to event  304 A. 
     After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  372 B with the DU  174  and CU  172 , similar to the UE assistance information procedure  372 A, thereby providing the preferred configuration (i.e., a first preferred configuration) to the DU  174 , which in turn provides the first preferred configuration to the CU  172 . 
     In response to receiving the first preferred configuration from the DU  174 , the CU  172  performs a DU reconfiguration procedure  374 B with the DU  174 , similar to the DU reconfiguration procedure  374 A, thereby receiving a DU configuration (i.e., a first DU configuration) from the DU  174  that indicates no more than the preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth indicated in the first preferred configuration. 
     In some implementations, after receiving the first DU configuration from the DU  174 , the CU  172  performs an RRC reconfiguration procedure  376 B with the DU  174  and UE  102 , similar to the RRC reconfiguration procedure  376 A. Thus, the UE  102  can update the multiple configuration parameters previously provided by the base station  104 A at event  302 B with the first DU configuration, and communicate with the DU  174  by using the updated configuration parameters. 
     Later in time (e.g., after the CU  172  detects that traffic of the UE  102  is inactive on the BS-terminated radio bearer(s)), the CU  172  determines to suspend a radio connection (e.g., including an RRC connection) with the UE  102 . In response to determining to suspend the radio connection, the CU  172  performs an RRC suspension procedure  378 B, similar to the RRC suspension procedure  378 A. As a result, the UE  102  suspends the radio connection, and can transition to an inactive state or an idle state. 
     Later in time after suspending the radio connection, the UE  102  can perform an RRC resume procedure  380 B to transition from the inactive or idle state to the connected state, similar to the RRC resume procedure  380 A. As a result, the UE  102  resumes  338 B the suspended radio connection and transitions to the connected state. The UE  102  can transmit  340 B an RRC resume complete message to the DU  174 , which in turn can send  342 B the RRC resume complete message to the CU  172 , similar to events  340 A and  342 A, respectively. 
     In some implementations, after the base station  104 A performs the RRC suspension procedure  378 B with the UE  102 , the UE  102  can retain  354 B the first preferred configuration (e.g., in response to receiving an RRC suspension message during the RRC suspension procedure  378 B). Similarly, in some implementations, the CU  172  can retain  353 B the first preferred configuration in response to determining to suspend the radio connection with the UE  102 . In other implementations, the UE  102  can retain  354 B the first preferred configuration in response to initiating the RRC resume procedure  380 B or during the RRC resume procedure  380 B. Similarly, in some implementations, the CU  172  can retain  353 B the first preferred configuration during the RRC resume procedure  380 B. 
     After the UE  102  resumes  338 B the suspended radio connection and transitions to the connected state, the UE  102  transmits  344 B another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the DU  174 . The DU  174  in turn sends  346 B the UE assistance information message to the CU  172 . 
     By sending the second preferred configuration to the CU  172  via the DU  174 , the UE  102  can override the first preferred configuration retained at the CU  172 , so that upon resuming connectivity with the CU  172 , the UE  102  and CU  172  can communicate using the second preferred configuration. As such, in contrast to releasing the first preferred configuration described above with respect to  FIG.  3 A , the UE  102  and the CU  172  can alternatively retain the first preferred configuration, yet override the first preferred configuration with the second preferred configuration for use after resuming connectivity. 
     The UE  102  can transmit  344 B the second preferred configuration for different reasons in various scenarios and implementations. In one implementation, the UE  102  can transmit the second preferred configuration if the UE  102  is satisfied with configuration parameters in the BS configuration that are used by the UE  102  to communicate with the base station  104 A, as described in event  302 A (i.e., the configuration parameters satisfy the preferences of the UE  102  as defined in the second preferred configuration). In another implementation, the UE  102  can transmit the second preferred configuration if the UE  102  no longer experiences an overheating situation, no longer detects low battery power, or otherwise no longer determines to conserve power. In another implementation, the UE  102  can transmit the second preferred configuration if the UE  102  experiences a different overheating situation (e.g., less severe situation or more severe situation) or determines to conserve less or more power. In another implementation, the UE  102  can transmit the second preferred configuration if the UE  102  experiences more overheating than the overheating situation that triggered the UE  102  to generate the first preferred configuration. 
     In response to receiving  346 B the UE assistance information message from the DU  174 , the CU  172  sends  362 B a fourth interface message (e.g., UE Context Modification Request message) including the second preferred configuration to the DU  174 . In some implementations, the DU  174  generates  364 B another DU configuration (i.e., a second DU configuration) for the UE  102  in response to the second preferred configuration if the configuration parameters at the UE  102  that were updated as a result of receiving the first DU configuration during the RRC reconfiguration procedure  376 B do not satisfy the second preferred configuration, or if the DU  174  determines to modify the configuration parameters despite the configuration parameters satisfying the second preferred configuration. The DU  174  generates the second DU configuration in a manner that would not exceed the capabilities of the UE  102 , e.g., by considering the UE capabilities. 
     In some scenarios and implementations, the UE  102  can send the second preferred configuration to the base station  104 A to request that the base station  104 A generate a second DU configuration that would not maximize capabilities of the UE  102  as defined in the UE capabilities. For example, in response to receiving the second preferred configuration from the UE  102  that indicates a preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth that is less than the corresponding maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth supported by the UE capabilities but greater than the corresponding maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth as indicated in the first preferred configuration, the base station  104 A can generate a second DU configuration that indicates no more than the preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth indicated in the second preferred configuration. As another example, the second preferred configuration can indicate the same number of SCell(s), MIMO layer(s), and/or aggregated bandwidth that are supported by the UE capabilities or as indicated in the BS configuration. 
     After the DU  174  generates the second DU configuration at event  364 B, the DU  174  can then send  366 B a fourth interface message (e.g., UE Context Modification Response message, UE Context Modification Required message) including the second DU configuration to the CU  172 . In other implementations, in response to receiving  362 B the second preferred configuration, the DU  174  need not generate the second DU configuration if the configuration parameters in the first preferred configuration satisfy the second preferred configuration. In this case, the DU  174  may omit the second DU configuration in the fourth interface message, or may include a second DU configuration irrelevant to the first preferred configuration in the fourth interface message. In response to receiving the fourth interface message from the DU  174 , the CU  172  can send a UE Context Modification Confirm message to the DU  174 . The events  362 B,  364 B, and  366 B are collectively referred to in  FIG.  3 B  as a second DU reconfiguration procedure  382 B. 
     In some implementations, after receiving the second DU configuration from the DU  174 , the CU  172  sends  317 B an RRC reconfiguration message including the second DU configuration to the DU  174 , which in turn transmits  319 B the RRC reconfiguration message to the UE  102 . In response, the UE  102  can transmit  321 B an RRC reconfiguration complete message to the DU  174 , which in turn sends  323 B the RRC reconfiguration complete message to the CU  172 . Thus, the UE  102  can update the multiple configuration parameters that were previously updated in accordance with the first preferred configuration with the second DU configuration, and communicate with the DU  174  by using the updated configuration parameters. In some implementations, the CU  172  can send  317 B a DL RRC Message Transfer message including the RRC reconfiguration message to the DU  174 , which in turn can send  323 B a UL RRC Message Transfer message including the RRC reconfiguration complete message to the CU  172 . The events  317 B,  319 B,  321 B, and  323 B are collectively referred to in  FIG.  3 B  as a second RRC reconfiguration procedure  384 B. 
     Referring now to  FIG.  3 C , in a scenario  300 C, the base station  104 A again operates as a serving base station for UE  102 , similar to scenario  300 A. Whereas in  FIG.  3 A  the UE  102  and the base station  104 A perform the RRC suspension procedure prior to the UE  102  and the base station  104 A releasing the first preferred configuration, in  FIG.  3 C  the UE  102  and the base station  104 A release the first preferred configuration prior to performing the RRC suspension procedure. Generally, the CU  172  and DU  174  in  FIG.  3 C  can perform similar actions as the CU  172  and DU  174  in  FIG.  3 A , respectively. 
     Initially, the UE  102  operates in a connected state and communicates  302 C data with the CU  172  and the DU  174  via cell  124 A by using a BS configuration, which includes multiple configurations, each corresponding to a respective configuration parameter, similar to event  302 A. 
     Later in time, the UE  102  and base station  104 A perform a UE assistance configuration procedure  304 C, a UE assistance information procedure  372 C, a DU reconfiguration procedure  374 C, and then an RRC reconfiguration procedure  376 C, similar to events  304 A,  372 A,  374 A, and  376 A, respectively. 
     After performing the RRC reconfiguration procedure  376 C, the UE  102  and the base station  104 A perform  382 C a UE assistance release procedure. During the UE assistance release procedure, the CU  172  can transmit an RRC message (e.g., an RRC reconfiguration message or a newly defined RRC message) to the UE  102  via the DU  174  to instruct the UE  102  to release the first preferred configuration, in some implementations. Subsequently, in some implementations, the UE  102  can release  352 C the first preferred configuration, and the CU  172  can release  351 C the first preferred configuration, similar to events  352 A and  351 A, respectively. In some implementations, the UE  102  can release the OtherConfig IE, the overheating configuration, and/or the power saving configuration in response to the UE assistance release procedure. The UE  102  can disable transmission of a UE assistance information message in response to releasing the OtherConfig IE, the overheating configuration, and/or the power saving configuration. Similarly, in some implementations, the CU  172  can release the OtherConfig IE, the overheating configuration, and/or the power saving configuration in response to the UE assistance release procedure. 
     Later in time (e.g., after the CU  172  detects that traffic of the UE  102  is inactive on the BS-terminated radio bearer(s)), the CU  172  determines to suspend a radio connection (e.g., including an RRC connection) with the UE  102 . In response to determining to suspend the radio connection, the CU  172  performs an RRC suspension procedure  378 C, similar to the RRC suspension procedure  378 A. As a result, the UE  102  suspends the radio connection, and can transition to an inactive state or an idle state. 
     After suspending the radio connection, the UE  102  can perform an RRC resume procedure  380 C to transition from the inactive or idle state to the connected state, similar to the RRC resume procedure  380 A. As a result, the UE  102  resumes  338 C the suspended radio connection and transitions to the connected state. The UE  102  can transmit  340 C an RRC resume complete message to the DU  174 , which in turn can send  342 C the RRC resume complete message to the CU  172 , similar to events  340 A and  342 A, respectively. 
     Now referring to  FIGS.  4 A- 4 B , the UE  102  resumes the suspended radio connection with a disaggregated base station, and subsequently provides a preferred configuration to the CU of the disaggregated base station. The CU can transmit the preferred configuration to a DU of the disaggregated base station, or release the preferred configuration. 
     Referring first to  FIG.  4 A , in a resume scenario  400 A, a source base station (S-BS)  104 B operates as a serving base station for UE  102 , similar to the serving base station  104 A in scenario  300 B. Whereas in  FIG.  3 B  the UE  102  resumes the suspended radio connection with the same serving base station  104 A and subsequently provides a second preferred configuration to the serving base station  104 A, in  FIG.  4 A  the UE  102  resumes the suspended radio connection with a target base station (e.g., T-BS  104 A) in a handover scenario, and subsequently provides the second preferred configuration to the target base station. In some implementations, the S-BS  104 B in  FIG.  4 A  can be a distributed base station like the base station  104 A in scenario  300 B, and thus perform similar actions as the CU  172  and DU  174  in  FIG.  3 B , respectively. In another implementation, the S-BS  104 B is an aggregated base station. In yet another implementation, the S-BS  104 B and the T-BS  104 A can share the same CU (i.e., T-CU  172 ), and thus the S-BS  104 B and the T-BS  104 A can be the same base station with two DUs. As such, in this implementation, messages described below that are exchanged between S-BS  104 B and the T-BS  104 A as separate base stations need not be exchanged. For ease of illustration, in  FIG.  4 A , the S-BS  104 B is depicted as an aggregated base station, and the T-BS  104 A is depicted as a distributed base station including a T-CU  172  and a T-DU  174 . 
     Initially, the UE  102  operates in a connected state and communicates  402 A data with the S-BS  104 B via cell  124 B by using an S-BS configuration, which includes multiple configurations, each corresponding to a respective configuration parameter, similar to event  302 B. 
     Later in time, the S-BS  104 B performs  404 A a UE assistance configuration procedure with the UE  102  to enable the UE  102  to transmit a preferred configuration to the S-BS  104 B, similar to event  304 B. 
     After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  472 A with the S-BS  104 B, similar to the UE assistance information procedure  372 B, thereby providing the preferred configuration (i.e., a first preferred configuration) to the S-BS  104 B. 
     In response to receiving the first preferred configuration from the UE  102 , the S-BS  104 B performs a DU reconfiguration procedure  474 A, similar to the DU reconfiguration procedure  374 B, thereby generating a DU configuration (i.e., a first DU configuration) that indicates no more than the preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth indicated in the first preferred configuration. 
     In some implementations, after generating the first DU configuration, the S-BS  104 B performs an RRC reconfiguration procedure  476 A with the UE  102 , similar to the RRC reconfiguration procedure  376 B. Thus, the UE  102  can update the multiple configuration parameters previously provided by the S-BS  104 B at event  402 A with the first DU configuration, and communicate with the S-BS  104 B by using the updated configuration parameters. 
     Later in time (e.g., after the S-BS  104 B detects that traffic of the UE  102  is inactive on the S-BS-terminated radio bearer(s)), the S-BS  104 B determines to suspend a radio connection (e.g., including an RRC connection) with the UE  102 . In response to determining to suspend the radio connection, the S-BS  104 B performs an RRC suspension procedure  478 A, similar to the RRC suspension procedure  378 B. As a result, the UE  102  suspends the radio connection, and can transition to an inactive state or an idle state. 
     In some implementations, the S-BS  104 B need not generate the first DU configuration if the configuration parameters in the S-BS configuration satisfy the first preferred configuration. In these implementations, the S-BS  104 B need not perform the DU reconfiguration procedure  474 A and the RRC reconfiguration procedure  476 A before the RRC suspension procedure  478 A. The S-BS  104 B may not perform the DU reconfiguration procedure  474 A and the RRC reconfiguration procedure  476 A for other reasons, such as when the S-BS  104 B is transmitting a high volume of data to the UE  102 , or is otherwise busy, for example. 
     Later in time after suspending the radio connection, the UE  102  can perform an RRC resume procedure  480 A to transition from the inactive or idle state to the connected state. In contrast to the UE  102  performing the RRC resume procedure  380 B with the same serving base station  104 A described in  FIG.  3 B , the UE  102  in  FIG.  4 A  performs the RRC resume procedure  480 A with the T-BS  104 A. Particularly, in the RRC resume procedure  480 A, the UE  102  transmits  430 A an RRC resume request message to the T-DU  174 , which in turn sends  432 A the RRC resume request message to the T-CU  172 . According to the RRC resume request message, the T-CU  172  addresses the S-BS  104 B (e.g., a source CU of the S-BS  104 B) and sends  492 A a Retrieve UE Context Request message to the S-BS  104 B to retrieve a UE context of the UE  102 . The S-BS  104 B sends  494 A a Retrieve UE Context Response message including the first preferred configuration to the T-CU  172 . The S-BS  104 B may also include the S-B S configuration in the Retrieve UE Context Response message. Then the T-CU  172  can send  496 A a UE Context Setup Request message including the first preferred configuration to the T-DU  174 . In some implementations, if the Retrieve UE Context Response message includes the S-B S configuration, the T-CU  172  can include, in the UE Context Setup Request message, an S-DU configuration that is contained in the S-BS configuration, and send  496 A the UE Context Setup Request message to the T-DU  174 , enabling the T-DU  174  to generate a T-DU configuration, i.e., a delta T-DU configuration augmenting the S-DU configuration. In other implementations, the T-CU  172  omits the S-DU configuration, to enable the T-DU  174  to generate a full T-DU configuration (i.e., a complete and self-contained T-DU configuration). The T-DU  174  then sends  498 A a UE Context Setup Response message, including the T-DU configuration, to the T-CU  172 . 
     In response to the RRC resume request message received at event  432 A, the T-CU  172  sends  434 A an RRC resume message including the T-DU configuration to the T-DU  174 , which in turn transmits  436 A the RRC resume message to the UE  102 , thereby completing the RRC resume procedure  480 A. As a result, the UE  102  resumes  438 A the suspended radio connection with the T-BS  104 A, and transitions to the connected state. The UE  102  can transmit  440 A an RRC resume complete message to the T-DU  174 , which in turn can send  442 A the RRC resume complete message to the T-CU  172 , similar to events  340 B and  342 B, respectively. 
     In some implementations, after the S-BS  104 B performs the RRC suspension procedure  478 A with the UE  102 , the UE  102  can retain  454 A the first preferred configuration (e.g., in response to receiving an RRC suspension message during the RRC suspension procedure  478 A). Similarly, in some implementations, the S-BS  104 B can retain  453 A the first preferred configuration in response to determining to suspend the radio connection with the UE  102 . In other implementations, the UE  102  can retain  454 A the first preferred configuration in response to initiating the RRC resume procedure  480 A or during the RRC resume procedure  480 A. Similarly, in some implementations, the S-BS  104 B can retain  453 A the first preferred configuration during the RRC resume procedure  480 A. 
     As discussed above in  FIG.  3 B , in some implementations, the UE  102  and the S-BS  104 B in  FIG.  4 A  can either release or retain some or all configurations in the S-BS configuration. Further, in some implementations, while the UE  102  is in inactive state or idle state, the UE  102  can retain the current security keys, a ROHC state if ROHC is configured at the UE  102 , QoS flow to DRB mapping rules, a C-RNTI used in a source PCell (e.g., PCell  124 B), a cell identity and a physical cell identity of the source PCell, and other configuration parameters in an RLC configuration, a MAC configuration, and/or a physical layer configuration. In some implementations, while the UE  102  is in inactive state or idle state, the UE  102  can retain the field or IE that enables the UE  102  to transmit the first preferred configuration. In other implementations, the UE  102  can release configurations within ReconfigurationWithSync IE and/or ServingCellConfigCommonSlB IE and/or the field or IE that enables the UE  102  to transmit the first preferred configuration in response to the RRC suspension message in the RRC suspension procedure  478 A or during the RRC resume procedure  480 A. 
     After the UE  102  resumes  438 A the suspended radio connection and transitions to the connected state, the UE  102  transmits  444 A another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the T-DU  174 , similar to event  344 B, for similar reasons described above with respect to  FIG.  3 B . The T-DU  174  in turn sends  446 A the UE assistance information message to the T-CU  172 , similar to event  346 B. By sending the second preferred configuration to the T-CU  172 , the UE  102  can override the first preferred configuration retained at the T-CU  172 , so that upon resuming connectivity with the T-CU  172 , the UE  102  and T-CU  172  can then communicate using the second preferred configuration. Then the T-CU  172  performs  482 A a DU reconfiguration procedure with the T-DU  174 , thereby generating a second DU configuration, similar to procedure  382 B, which causes the T-CU  172  to perform  484 A an RRC reconfiguration procedure with the UE  102 , similar to the RRC reconfiguration procedure  384 B. Thus, the UE  102  can update the multiple configuration parameters that were previously updated in accordance with the first preferred configuration with the second DU configuration, and communicate with the T-DU  174  by using the updated configuration parameters. 
     Referring now to  FIG.  4 B , in a resume scenario  400 B, the S-BS  104 B again operates as a serving base station for UE  102 . Whereas in  FIG.  4 A  the UE  102  and the S-BS  104 B retain the first preferred configuration, in  FIG.  4 B  the UE  102  and the S-BS  104 B release the first preferred configuration. Generally, the S-BS  104 B and T-BS  104 A in  FIG.  4 B  can perform similar actions as the S-BS  104 B and T-BS  104 A in  FIG.  4 A , respectively. 
     Initially, the UE  102  operates in a connected state and communicates  402 B data with the S-BS  104 B via cell  124 B by using an S-BS configuration, which includes multiple configurations, each corresponding to a respective configuration parameter, similar to event  402 A. 
     Later in time, the S-BS  104 B performs  404 B a UE assistance configuration procedure with the UE  102  to enable the UE  102  to transmit a preferred configuration to the S-BS  104 B, similar to event  404 A. 
     After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  472 B with the S-BS  104 B, similar to the UE assistance information procedure  472 A, thereby providing the preferred configuration (i.e., a first preferred configuration) to the S-BS  104 B. 
     In response to receiving the first preferred configuration from the UE  102 , the S-BS  104 B performs a DU reconfiguration procedure  474 B, similar to the DU reconfiguration procedure  474 A, thereby generating a DU configuration (i.e., a first DU configuration) that indicates no more than the preferred maximum number of SCell(s), MIMO layer(s), and/or aggregated bandwidth indicated in the first preferred configuration. 
     In some implementations, after generating the first DU configuration, the S-BS  104 B performs an RRC reconfiguration procedure  476 B with the UE  102 , similar to the RRC reconfiguration procedure  476 A. Thus, the UE  102  can update the multiple configuration parameters previously provided by the S-BS  104 B at event  402 B with the first DU configuration, and communicate with the S-BS  104 B by using the updated configuration parameters. 
     Later in time (e.g., after the S-BS  104 B detects that traffic of the UE  102  is inactive on the S-BS-terminated radio bearer(s)), the S-BS  104 B determines to suspend a radio connection (e.g., including an RRC connection) with the UE  102 . In response to determining to suspend the radio connection, the S-BS  104 B performs an RRC suspension procedure  478 B, similar to the RRC suspension procedure  478 A. As a result, the UE  102  suspends the radio connection, and can transition to an inactive state or an idle state. 
     In some implementations, after the S-BS  104 B performs the RRC suspension procedure  478 B with the UE  102 , the UE  102  can release  456 B the first preferred configuration (e.g., in response to receiving an RRC suspension message during the RRC suspension procedure  478 B). In other implementations, the UE  102  can release  456 B the first preferred configuration in response to initiating the RRC resume procedure  480 B or during the RRC resume procedure  480 B, as will be further described below. 
     Later in time after suspending the radio connection, the UE  102  can perform the RRC resume procedure  480 B to transition from the inactive or idle state to the connected state. Particularly, in the RRC resume procedure  480 B, the UE  102  transmits  430 B an RRC resume request message to the T-DU  174 , which in turn sends  432 B the RRC resume request message to the T-CU  172 . According to the RRC resume request message, the T-CU  172  addresses the S-BS  104 B and sends  492 B a Retrieve UE Context Request message to the S-BS  104 B to retrieve a UE context of the UE  102 . The S-BS  104 B sends  494 B a Retrieve UE Context Response message including the first preferred configuration to the T-CU  172 . The S-BS  104 B may also include the S-BS configuration in the Retrieve UE Context Response message. Then the T-CU  172  releases  455 B the first preferred configuration and sends  496 B a UE Context Setup Request message (i.e., omitting the first preferred configuration) to the T-DU  174 . In some implementations, if the Retrieve UE Context Response message includes the S-BS configuration, the T-CU  172  can include, in the UE Context Setup Request message, an S-DU configuration that is contained in the S-BS configuration, and send  496 B the UE Context Setup Request message to the T-DU  174 , enabling the T-DU  174  to generate a T-DU configuration, i.e., a delta T-DU configuration augmenting the S-DU configuration. In other implementations, the T-CU  172  omits the S-DU configuration, to enable the T-DU  174  to generate a full T-DU configuration (i.e., a complete and self-contained T-DU configuration). The T-DU  174  then sends  498 B a UE Context Setup Response message, including the T-DU configuration, to the T-CU  172 . 
     In response to the RRC resume request message received at event  432 B, the T-CU  172  sends  434 B an RRC resume message including the T-DU configuration to the T-DU  174 , which in turn transmits  436 B the RRC resume message to the UE  102 , thereby completing the RRC resume procedure  480 B. As a result, the UE  102  resumes  438 B the suspended radio connection with the T-BS  104 A, and transitions to the connected state. The UE  102  can transmit  440 B an RRC resume complete message to the T-DU  174 , which in turn can send  442 B the RRC resume complete message to the T-CU  172 , similar to events  440 A and  442 A, respectively. 
     By releasing the first preferred configuration at the UE  102  and the T-CU  172  at events  456 B and  455 B, respectively, the UE  102  and the T-CU  172  need not be limited to communicating with each other according to the first preferred configuration upon resuming the suspended radio connection. For example, the UE  102  may have recovered from an overheating situation or increased battery power since the inactive state or an idle state, such that the UE  102  is able to utilize more SCell(s), MIMO layer(s), and/or aggregated bandwidth than those indicated in the first preferred configuration after transitioning back to the connected state. Because the UE  102  and the T-CU  172  are still aware of the S-BS configuration (including the updated configuration parameters configured by the RRC reconfiguration procedures  476 B), the UE  102  and the T-CU  172  may proceed to communicate using the S-BS configuration again, for example. 
     In some implementations, the T-CU  172  can obtain another DU configuration (i.e., second DU configuration) from the T-DU  174 , e.g., by using a UE Context Setup procedure (e.g., as described in  FIG.  4 A  above), and include the second DU configuration in the RRC resume message. In another such implementation, the CU  172  can generate configuration(s) and include the generated configuration(s) in the RRC resume message. In other implementations, after receiving the RRC resume complete message, the T-CU  172  can obtain another DU configuration (i.e., second DU configuration) from the T-DU  174 , e.g., by using a DU reconfiguration procedure (similar to the DU reconfiguration procedure  374 A) and perform an RRC reconfiguration procedure with the UE  102 , similar to the RRC reconfiguration procedure  376 A. The CU  172  can include the second DU configuration in an RRC reconfiguration message in the RRC reconfiguration procedure. Because the T-CU  172  releases the first preferred configuration at event  455 B, the T-CU  172  does not send the first preferred configuration to the T-DU  174  during the DU reconfiguration procedure or the UE Context Setup procedure. Therefore, the T-DU  174  generates the second DU configuration in a manner that would not underestimate the capabilities of the UE  102 , e.g., by considering the UE capabilities rather than the first preferred configuration. 
     Now referring to  FIGS.  5 A- 5 G , the UE  102  is in DC with an MN and an SN, and later disconnects from the SN. In various scenarios, the UE  102  can release or retain a preferred configuration upon disconnecting from the SN. 
     Referring first to  FIG.  5 A , in a scenario  500 A, the base station  104 A operates as an MN for the UE  102 , and the base station  106 A operates as an SN for the UE  102 . In some implementations, the SN  106 A is a distributed base station that includes a CU and a DU, where the CU can exchange SN messages with the MN  104 A and exchange RRC messages with the UE  102  via the MN  104 A, as further described below. For ease of illustration, the SN  106 A is depicted as an aggregated base station. In this implementation, the UE  102  releases the first preferred configuration upon SN release. 
     Initially, the UE  102  communicates  502 A data in SC with the MN  104 A via cell  124 A by using an MN configuration, which is similar to the BS configuration described above with respect to  FIG.  3 A , for example. In other implementations and scenarios, the UE  102  communicates  502 A data in DC with the MN  104 A via PCell  124 A by using the MN configuration, and with a source SN (S-SN) (e.g., S-SN  106 B via PSCell  126 B) by using an S-SN configuration. In this scenario, the SN  106 A depicted in  FIG.  5 A  is a target SN (T-SN). In some implementations, during event  502 A, the MN  104 A can receive UE capabilities of the UE  102  from the UE  102 , the CN  110  (e.g., an MME  114  or AMF  164 ), or another base station (e.g., base station  104 B). 
     Later in time, the MN  104 A determines  504 A to initiate an SN addition procedure for the SN  106 A and the UE  102  to communicate, e.g., blindly or in response to detecting a suitable event. For example, the determination  504 A can occur in response to the MN  104 A receiving one or more measurement results from the UE  102  that are above (or below) one or more predetermined thresholds, or calculating a filtered result (from the measurement result(s)) that is above (or below) a predetermined threshold. In another example, the suitable event can be that the UE  102  is moving toward the SN  106 A. In yet another example, the suitable event can be one or more measurement results, generated or obtained by the MN  104 A based on measurements of signals received from the UE  102 , being above (or below) one or more predetermined thresholds. In yet another example, the determination  504 A can occur in response to the MN  104 A receiving an SN Change Required message from an S-SN (e.g., S-SN  106 B). 
     After determining  504 A to initiate the SN addition procedure, the MN  104 A sends  506 A an SN Addition Request message including UE capabilities of the UE  102  to the SN  106 A. In turn, the SN  106 A can generate a DU configuration (i.e., a first DU configuration) in a manner that would not exceed the capabilities of the UE  102 , e.g., by considering the UE capabilities. In some implementations, if the SN  106 A is a T-SN, the MN  104 A can also include the S-SN configuration associated with the S-SN (e.g., S-SN  106 B) in the SN Addition Request message. 
     If the SN  106 A is a distributed base station that consists of a CU and DU, the CU sends a UE Context Setup Request message to the DU to obtain the first DU configuration for the UE  102  in response to receiving the SN Addition Request message. In response to the UE Context Setup Request message, the DU sends a UE Context Setup Response message including the first DU configuration to the CU. The CU can include the UE capabilities in the UE Context Setup Request message, and the DU can generate the first DU configuration in a manner that would not exceed the UE capabilities. In some implementations, the CU can include the S-SN configuration or an S-DU configuration in the S-SN configuration in the UE Context Setup Request message. The DU can generate the first DU configuration as a delta DU configuration which augments a portion of the S-SN configuration or the S-DU configuration. In other implementations, the DU can generate the first DU configuration as a full DU configuration which is a complete and self-contained DU configuration. The first DU configuration and the S-DU configuration are similar to the DU configuration as described above with respect to  FIG.  3 A . 
     In response to receiving the SN Addition Request message, the SN  106 A sends  516 A an SN Addition Request Acknowledge message including the first DU configuration to the MN  104 A. In turn, the MN  104 A transmits  517 A an RRC container message including the first DU configuration to the UE  102 . In response to the RRC container message, the UE  102  transmits  518 A an RRC container response message to the MN  104 A, which in turn sends  520 A an SN Reconfiguration Complete message to the SN  106 A. In some implementations, the SN  106 A generates an RRC reconfiguration message that includes the first DU configuration, includes the RRC reconfiguration message in the SN Addition Request Acknowledge message, and sends  516 A the SN Addition Request Acknowledge message to the MN  104 A. In turn, the MN  104 A transmits  517 A the RRC container message including the RRC reconfiguration message to the UE  102 . In some implementations, the UE  102  may include an RRC reconfiguration complete message in the RRC container response message, and the MN  104 A in turn includes the RRC reconfiguration complete message in the SN Reconfiguration Complete message at event  520 A. In some implementations, the SN  106 A can include a measurement configuration (e.g., MeasConfig IE) in the RRC reconfiguration message. 
     In implementations in which the MN  104 A receives an SN Change Required message from an S-SN (e.g., S-SN  106 B), the MN  104 A may send an SN Change Confirm message to the S-SN in response to the SN Change Required message, e.g., before or after receiving the RRC container response message or the SN Addition Request Acknowledge message. In some implementations, the MN  104 A may send an SN Release Request message to the S-SN after determining  504 A to initiate the SN addition procedure. The S-SN may send an SN Release Request Acknowledge message to the MN  104 A in response. 
     In some implementations, the SN  106 A (e.g., the CU of the SN  106 A) can generate a CU configuration. For example, the CU configuration can be a radio bearer configuration (RadioBeareConfig IE). The SN  106 A can include the CU configuration in the SN Addition Request Acknowledge message at event  516 A and the MN  104 A can include the CU configuration in the RRC container message at event  517 A. The CU configuration can be a full CU configuration, which is a complete and self-contained CU configuration, or a delta CU configuration, which augments a source CU configuration (e.g., RadioBeareConfig IE) in the S-SN configuration. 
     The first DU configuration or the RRC reconfiguration message described above also includes one or more random access configurations needed by the UE  102  to connect to the SN  106 A (e.g., the DU of the SN  106 A), and in some implementations, includes additional fields, such as a mobility field (e.g., mobilityControlInfoSCG field or a ReconfigurationWithSync IE), which can include some or all of the random access configurations. 
     In response to receiving  517 A the first DU configuration or the RRC reconfiguration message, the UE  102  performs  522 A a random access procedure with the SN  106 A (e.g., the DU of the SN  106 A), e.g., by using one or more random access configurations in the first DU configuration or the RRC reconfiguration message. After the SN  106 A (e.g., the DU of the SN  106 A) identifies the UE  102  during the random access configuration (e.g., the UE  102  succeeds the contention resolution), the UE  102  communicates  526 A control signals and data in DC with the MN  104 A and with the SN  106 A (e.g., the DU of the SN  106 A) by using the first DU configuration. In implementations in which the MN  104 A includes the CU configuration in the RRC container message at event  517 A, the UE  102  can communicate  526 A data with the SN  106 A (e.g., the CU of the SN  106 A) by using either the full CU configuration or the delta CU configuration and a portion of the source CU configuration. After the SN  106 A (e.g., the DU of the SN  106 A) identifies the UE  102  during the random access configuration (e.g., the UE  102  succeeds the contention resolution), the DU of the SN  106 A may send a Downlink Data Delivery Status message to the CU of the SN  106 A in response to identifying the UE  102  during the random access procedure. The events  504 A,  506 A,  516 A,  517 A,  518 A,  520 A,  522 A, and  526 A are collectively referred to in  FIG.  5 A  as a DC configuration procedure  560 A. 
     After the UE  102  connects to the SN  106 A at event  522 A, either the MN  104 A or the SN  106 A can initiate  528 A a UE assistance configuration procedure with the UE  102  to enable the UE  102  to transmit a preferred configuration, similar to event  304 A. In an MN-initiated UE assistance configuration procedure, the MN  104 A can configure the UE  102  to indirectly provide the preferred configuration to the SN  106 A via the MN  104 A. In an SN-initiated UE assistance configuration procedure, the SN  106 A can configure the UE  102  to either directly provide the preferred configuration to the SN  106 A, or indirectly provide the preferred configuration to the SN  106 A via the MN  104 A. 
     For example, during the SN-initiated UE assistance configuration procedure, the SN  106 A can transmit an RRC message to the UE  102  via the MN  104 A, or broadcast an RRC message via PSCell  126 A, to enable the UE  102  to transmit a preferred configuration, and in turn, the UE  102  can transmit an RRC response message to the SN  106 A via the MN  104 A, in some implementations. In other implementations, the SN  106 A can include a field/IE in the RRC reconfiguration message at event  516 A for enabling transmission of a preferred configuration. 
     The SN  106 A can enable the UE  102  to transmit the preferred configuration if the UE capabilities indicate support of transmitting the preferred configuration to the SN  106 A. In some implementations, the UE  102  can indicate support of transmitting a preferred configuration to the SN  106 A in a capability IE for the SN  106 A. For example, if the SN  106 A is a gNB, the capability IE is a UE-NR-Capability or a UE-MRDC-Capability. If the SN  106 A is an ng-eNB, the capability IE is a UE-EUTRA-Capability or a UE-MRDC-Capability. In some implementations, the UE  102  can indicate support of transmitting a preferred configuration to the SN  106 A in a capability IE for the MN  104 A. 
     If the UE capabilities do not indicate support of transmitting the preferred configuration to the SN  106 A, the SN  106 A does not enable the UE  102  to transmit the preferred configuration to the SN  106 A. For example, if the UE capabilities indicate support of transmitting a preferred configuration only to the MN  104 A, the SN  106 A does not enable the UE  102  to transmit the preferred configuration to the SN  106 A. In some implementations, the UE  102  can indicate support of transmitting a preferred configuration to the MN  104 A in a capability IE for the MN  104 A. For example, if the MN  104 A is a gNB, the capability IE is a UE-NR-Capability. If the MN is an eNB or ng-eNB, the capability IE is a UE-EUTRA-Capability. In some implementations, the UE  102  can indicate support of indirectly transmitting a preferred configuration to the SN  106 A via the MN  104 A in a capability IE for the MN  104 A. For example, if the MN  104 A is a gNB, the capability IE is a UE-NR-Capability. If the MN is an eNB or ng-eNB, the capability IE is a UE-EUTRA-Capability. 
     In some implementations, the SN  106 A can optionally update the first DU configuration (e.g., adding new configurations to the first DU configuration or modifying configurations in the first DU configuration) by transmitting an RRC reconfiguration message to the UE  102  via the MN  104 A. In response, the UE  102  can transmit an RRC reconfiguration complete message to the SN  106 A via the MN  104 A. For simplicity, the first DU configuration described with respect to  FIG.  5 A  can refer to the original first DU configuration or the updated first DU configuration. 
     After the UE  102  is enabled to transmit a preferred configuration, the UE  102  transmits  532 A a UE assistance information message including a first preferred configuration to the MN  104 A. The UE  102  can transmit  532 A the first preferred configuration for different reasons in various scenarios and implementations. In one implementation, the UE  102  can transmit the first preferred configuration if the UE  102  is not satisfied with configuration parameters in the first DU configuration that are used by the UE  102  to communicate with the SN  106 A, as described in event  526 A (i.e., the configuration parameters do not satisfy the preferences of the UE  102  as defined in the first preferred configuration). In another implementation, the UE  102  can transmit the first preferred configuration even if the UE  102  is satisfied with the configuration parameters, to prevent the SN  106 A from changing the configuration parameters that the UE  102  may not prefer. In some implementations, the UE  102  can transmit the first preferred configuration if the UE  102  experiences an overheating situation (e.g., due to heavy application processing), detects low battery power, or otherwise determines to conserve power. The UE  102  can transmit the first preferred configuration for power saving purposes (even if the UE  102  does not experience an overheating situation), overheating purposes, or both. 
     In response to receiving  532 A the UE assistance information message from the UE  102 , the MN  104 A in turn sends  534 A the UE assistance information message to the SN  106 A. The events  532 A and  534 A are collectively referred to in  FIG.  5 A  as a UE assistance information procedure  530 A. In some implementations, if SRB3 between the UE  102  and the SN  106 A is not configured, the UE  102  can transmit  532 A an ULInformationTransferMRDC message including the UE assistance information message to the MN  104 A via SRB1. In some implementations, if SRB3 between the UE  102  and the SN  106 A is configured and not suspended, the UE  102  can transmit  531 A the UE assistance information message to the SN  106 A via the SRB3 instead of transmitting the UE assistance information message to the SN  106 A via the MN  104 A (events  532 A and  534 A). In other implementations, if SRB3 between the UE  102  and the SN  106 A is configured and suspended, the UE  102  can transmit  532 A an ULInformationTransferMRDC message including the UE assistance information message to the MN  104 A via SRB1. In such a case, the UE  102  may not transmit to the MN  104 A via SRB1 an ULInformationTransferMRDC message including a MeasurementReport message associated to a measurement configuration configured by the SN  106 A. In yet other implementations, if SRB3 between the UE  102  and the SN  106 A is configured and suspended, the UE  102  can suspend transmission of the UE assistance information message (i.e., the UE  102  neither transmits the UE assistance information message to the MN  104 A nor the SN  106 A). After resuming SRB3, if the UE  102  determines a condition is still met for transmitting the UE assistance information message, the UE  102  can transmit the UE assistance information message to the SN  106 A on the SRB3. After resuming SRB3, if the UE  102  determines no condition is met for transmitting the UE assistance information message, the UE  102  abandons transmission of the UE assistance information message. If the UE  102  has generated the UE assistance information message and determines no condition is met for transmitting the UE assistance information message, the UE  102  can discard the UE assistance information message. 
     In response to receiving the UE assistance information message, the SN  106 A then generates  536 A a second DU configuration in response to receiving the first preferred configuration, similar to the manner in which the base station  104 A generates the DU configuration in the DU reconfiguration procedure  374 A described above with respect to  FIG.  3 A . That is, in implementations in which the SN  106 A is a distributed base station, the CU of the SN  106 A sends a first interface message including the first preferred configuration to the DU of the SN  106 A, the DU generates the second DU configuration, and the DU sends the second DU configuration in a second interface message to the CU. In some implementations, the SN  106 A may omit the second DU configuration in the second interface message, or may include a second DU configuration irrelevant to the first preferred configuration in the second interface message, similar to the manner in which the base station  104 A omits the DU configuration or includes the DU configuration irrelevant to the first preferred configuration in the second interface message in the DU reconfiguration procedure  374 A. 
     In some implementations, after generating the second DU configuration, the SN  106 A sends  538 A an RRC reconfiguration message including the second DU configuration to the MN  104 A, which in turn transmits  540 A the RRC reconfiguration message to the UE  102 . In response, the UE  102  can transmit  542 A an RRC reconfiguration complete message to the MN  104 A, which in turn sends  544 A the RRC reconfiguration complete message to the SN  106 A. Thus, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A at event  526 A in the first DU configuration with the second DU configuration, and communicate with the SN  106 A (e.g., the DU of the SN  106 A) by using the updated configuration parameters. In some implementations, the SN  106 A can send  538 A an SN message (e.g., SN Modification Required message, SN Modification Request Acknowledge message or RRC Transfer message) including the RRC reconfiguration message to the MN  104 A, which in turn can send  540 A an RRC container message including the RRC reconfiguration message to the UE  102 . The UE  102  can then transmit  542 A an RRC container response message including the RRC reconfiguration complete message to the MN  104 A, which in turn can send  544 A an SN message (e.g., SN Modification Request message, RRC Transfer message or SN Reconfiguration Complete message) including the RRC reconfiguration complete message to the SN  106 A. The events  538 A,  540 A,  542 A, and  544 A are collectively referred to in  FIG.  5 A  as an RRC reconfiguration procedure  570 A. 
     Although the SN  106 A is described as generating a single second DU configuration at event  536 A, the SN  106 A may generate multiple second DU configurations. If the SN  106 A generates multiple second DU configurations, the SN  106 A and the UE  102  can perform the RRC reconfiguration procedure  570 A multiple times so that the UE  102  can obtain the multiple second DU configurations. 
     As discussed above, in some implementations, in response to receiving  534 A the first preferred configuration, the SN  106 A need not generate the second DU configuration. In these implementations, the SN  106 A need not perform the DU reconfiguration procedure  536 A and the RRC reconfiguration procedure  570 A before the SN release procedure  546 A. The SN  106 A need not perform the DU reconfiguration procedure  536 A and the RRC reconfiguration procedure  570 A for other reasons, such as when the SN  106 A is transmitting a high volume of data to the UE  102 , or is otherwise busy, for example. 
     In some scenarios and implementations, after receiving the first preferred configuration at event  530 A, the SN  106 A can generate a C-DU configuration, similar to the manner in which the base station  104 A of  FIG.  3 A  generates the DU configuration in the DU reconfiguration procedure  374 A, to prepare a conditional configuration for conditional PSCell addition or change (CPAC) for the UE  102 . The SN  106 A can generate the C-DU configuration that satisfies the first preferred configuration. In other scenarios and implementations, either before or after event  530 A, the SN  106 A can generate a C-DU configuration according to the UE capabilities stored in the SN  106 A without taking the first preferred configuration into account. After the SN  106 A obtains the C-DU configuration, the SN  106 A generates an RRC message including the C-DU configuration, a conditional configuration including the RRC message, and an RRC reconfiguration message including the conditional configuration. Then the SN  106 A transmits the RRC reconfiguration message to the UE  102  via the MN  104 A or via an SRB (e.g., SRB3). Later, if the UE  102  detects that a condition for connecting to a candidate cell of the SN  106 A is satisfied, the UE  102  connects to the SN  106 A via the candidate cell (i.e., candidate PSCell). The SN  106 A can perform an RRC reconfiguration procedure with the UE  102  via the MN  104 A or the SRB to transmit another DU configuration satisfying the first preferred configuration to the UE  102 , similar to the DU reconfiguration procedure  536 A or  536 B and RRC reconfiguration procedure  570 A or  571 B. 
     If the SN  106 A transmits a conditional configuration (i.e., a first conditional configuration) to the UE  102  before receiving the first preferred configuration from the UE  102 , the SN  106 A may not update the conditional configuration even though the conditional configuration does not satisfy the first preferred configuration, in one implementation. In another implementation, if the conditional configuration does not satisfy the first preferred configuration, the SN  106 A can transmit an RRC reconfiguration message to the UE  102  for releasing the conditional configuration via the MN  104 A or the SRB. In yet another implementation, the CU  172  can transmit an RRC reconfiguration message to the UE  102  for releasing the conditional configuration via the MN  104 A or the SRB in response to receiving the first preferred configuration from the UE  102 . In yet another implementation, if the conditional configuration does not satisfy the first preferred configuration received from the UE  102 , the SN  106 A can transmit an RRC reconfiguration message including another conditional configuration (i.e., a second conditional configuration) to the UE  102  via the MN  104 A or the SRB to replace the first conditional configuration. The SN  106 A can obtain a new C-DU configuration satisfying the first preferred configuration and transmit the second conditional configuration including the new C-DU configuration to the UE  102  in a similar manner as described above. 
     In some scenarios and implementations, the UE  102  can be in SC with the MN  104 A or in DC with the MN  104 A and the SN  106 A as shown in  FIG.  5 A . After receiving the first preferred configuration from the UE  102 , the MN  104 A can perform a conditional DC configuration procedure (i.e., CSAC configuration procedure) with a candidate SN (C-SN) (e.g., C-SN  106 B) and the UE  102 , similar to the DC configuration procedure  560 A, to transmit a conditional configuration for CSAC to the UE  102 . The MN  104 A can include the first preferred configuration in an SN Addition Request message in the CSAC configuration procedure. Then the C-SN can generate a C-DU configuration satisfying the first preferred configuration and generate an RRC reconfiguration message including the C-DU configuration. The C-SN can send an SN Addition Request Acknowledge message including the RRC reconfiguration message to the MN  104 A in response to the SN Addition Request message. In turn, the MN  104 A generates a conditional configuration including the RRC reconfiguration message and transmits an RRC container message including the conditional configuration to the UE  102 . 
     In other scenarios and implementations, the UE  102  can be in SC with the MN  104 A or in DC with the MN  104 A and the SN  106 A as shown in  FIG.  5 A . Either before or after receiving the first preferred configuration, the MN  104 A can perform a CSAC configuration procedure with a C-SN (e.g., C-SN  106 B) and the UE  102 , similar to the DC configuration procedure  560 A, to transmit a conditional configuration for CSAC to the UE  102 . The MN  104 A can send an SN Addition Request message excluding the first preferred configuration in the CSAC configuration procedure. Then the C-SN can generate a C-DU configuration according to the UE capabilities and generate an RRC reconfiguration message including the C-DU configuration. The C-SN can send an SN Addition Request Acknowledge message including the RRC reconfiguration message to the MN  104 A in response to the SN Addition Request message. In turn, the MN  104 A generates a conditional configuration including the RRC reconfiguration message and transmits an RRC container message including the conditional configuration to the UE  102 . Later, if the UE  102  detects that a condition for connecting to a candidate cell of the C-SN is satisfied, the UE  102  connects to the C-SN via the candidate cell (i.e., candidate PSCell). If the C-SN receives the first preferred configuration from the UE  102  or the MN  104 A, the C-SN can perform an RRC reconfiguration procedure with the UE  102  via the MN  104 A or the SRB to transmit another DU configuration satisfying the first preferred configuration to the UE  102 , similar to the DU reconfiguration procedure  536 A or  536 B and RRC reconfiguration procedure  570 A or  571 B. 
     If the MN  104 A transmits a conditional configuration (i.e., a first conditional configuration) to the UE  102  before receiving the first preferred configuration from the UE  102 , the MN  104 A may not update the conditional configuration even though the conditional configuration does not satisfy the first preferred configuration, in one implementation. In another implementation, if the conditional configuration does not satisfy the first preferred configuration, the MN  104 A can transmit an RRC container message releasing the conditional configuration to the UE  102 . In yet another implementation, the MN  104 A can transmit an RRC container message to the UE  102  for releasing the conditional configuration in response to receiving the first preferred configuration from the UE  102 . In yet another implementation, if the conditional configuration does not satisfy the first preferred configuration received from the UE  102 , the MN  104 A can transmit an RRC container message including another conditional configuration (i.e., a second conditional configuration) to the UE  102  to replace the first conditional configuration. The MN  104 A can obtain an RRC reconfiguration message including a new C-DU configuration satisfying the first preferred configuration from the C-SN and transmit the second conditional configuration including the RRC reconfiguration message to the UE  102  in a similar manner as described above. 
     Later in time (e.g., after the MN  104 A or the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the MN  104 A or the SN  106 A determines to release the SN  106 A for the UE  102 . In an MN-initiated SN release procedure, the MN  104 A can initiate  546 A an SN release procedure with the SN  106 A to release the SN  106 A for the UE  102  (i.e., configure the UE  102  to be in SC). The MN  104 A sends an SN Release Request message to the SN  106 A, which in turn sends an SN Release Request Acknowledge message to the MN  104 A. Alternatively, in an SN-initiated SN release procedure, the SN  106 A can initiate  546 A the SN release procedure with the MN  104 A to release the SN  106 A for the UE  102 . The SN  106 A sends an SN Release Required message to the MN  104 A, which in turn sends an SN Release Confirm message to the SN  106 A. After either the MN  104 A or the SN  106 A determines to release the SN  106 A, the MN  104 A sends  548 A an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 . That is, the MN  104 A can send  548 A the RRC reconfiguration message to the UE  102  during the MN-initiated SN release procedure or the SN-initiated SN release procedure. As a result, the UE  102  disconnects  550 A from the SN  106 A and releases the first preferred configuration in response to releasing the SN  106 A. Because the second DU configuration received at event  540 A is unnecessary as a result of disconnecting  550 A from the SN  106 A, the UE  102  also releases the second DU configuration. The UE  102  then transmits  552 A an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message. Accordingly, the UE  102  in SC communicates  554 A with the MN  104 A after disconnecting from the SN  106 A. 
     In some implementations, the UE  102  can either release or retain some or all configurations in the second DU configuration in response to receiving the RRC reconfiguration message at event  548 A or in response to releasing the SN  106 A. If there are configuration(s) in the first DU configuration which have not been updated by the second DU configuration, the UE  102  can also release the configuration(s) in the first DU configuration in response to the RRC reconfiguration message at event  548 A or in response to releasing the SN  106 A. In some implementations, the UE  102  can release configurations within ReconfigurationWithSync IE and/or ServingCellConfigCommonSlB IE, and/or release or retain the field or IE that enables the UE  102  to transmit the first preferred configuration in response to receiving the RRC reconfiguration message at event  548 A or in response to releasing the SN  106 A. In some implementations, if the UE  102  receives the field or IE that enables the UE  102  to transmit the first preferred configuration in the MN-initiated UE assistance configuration procedure, the UE  102  can retain the field or IE in response to receiving the RRC reconfiguration message at event  548 A or in response to releasing the SN  106 A. In other implementations, if the UE  102  receives the field or IE that enables the UE  102  to transmit the first preferred configuration in the SN-initiated UE assistance configuration procedure, the UE  102  can release the field or IE in response to receiving the RRC reconfiguration message at event  548 A or in response to releasing the SN  106 A. 
     In some implementations, if the MN  104 A is a gNB, the RRC container message can be an RRCReconfiguration message and the RRC container response message can be an RRCReconfigurationComplete message. In other implementations, if the MN  104 A is an eNB or an ng-eNB, the RRC container message can be an RRCConnectionReconfiguration message and the RRC container response message can be an RRCConnectionReconfigurationComplete message. 
     In some implementations, if the SN  106 A is a gNB, the RRC reconfiguration message and the RRC reconfiguration complete message can be an RRCReconfiguration message and an RRCReconfigurationComplete message, respectively. In other implementations, if the SN  106 B is an eNB or an ng-eNB, the RRC reconfiguration message and the RRC reconfiguration complete message can be an RRCConnectionReconfiguration message and an RRCConnectionReconfigurationComplete message, respectively. 
     Referring now to  FIG.  5 B , in a scenario  500 B, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  5 A  the UE  102  sends the first preferred configuration to the SN  106 A via the MN  104 A, in  FIG.  5 B  the UE  102  sends the first preferred configuration directly to the SN  106 A. Consequently, the SN  106 A sends the second DU configuration directly to the UE  102 . 
     Initially, the UE  102  communicates  502 B data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 A. Later in time, the MN  104 A performs a DC configuration procedure  560 B, similar to the DC configuration procedure  560 A. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A (e.g., the DU of the SN  106 A) by using a first DU configuration received from the MN  104 A during the DC configuration procedure  560 B. 
     After the UE  102  connects to the SN  106 A, either the MN  104 A or the SN  106 A can initiate  528 B a UE assistance configuration procedure with the UE  102 , similar to event  528 A, to enable the UE  102  to transmit a preferred configuration directly to the SN  106 A. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  531 B by transmitting a UE assistance information message including a first preferred configuration directly to the SN  106 A for different reasons in various scenarios and implementations, as discussed above with respect to  FIG.  5 A . The SN  106 A then generates  536 B a second DU configuration in response to receiving the first preferred configuration, similar to event  536 A. 
     In some implementations, after generating the second DU configuration, the SN  106 A sends  539 B an RRC reconfiguration message including the second DU configuration directly to the UE  102 . In response, the UE  102  can transmit  543 B an RRC reconfiguration complete message directly to the SN  106 A. SRB3 resources can enable the UE  102  and the SN  106 A to exchange the RRC reconfiguration message and the RRC reconfiguration complete message. Thus, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A during the DC configuration procedure  560 B in the first DU configuration with the second DU configuration, and communicate with the SN  106 A by using the updated configuration parameters. The events  539 B and  543 B are collectively referred to in  FIG.  5 B  as an RRC reconfiguration procedure  571 B. 
     Later in time (e.g., after the MN  104 A or the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the MN  104 A or the SN  106 A can initiate  546 B an SN release procedure to release the SN  106 A for the UE  102 , similar to event  546 A. After either the MN  104 A or the SN  106 A determines to release the SN  106 A, the MN  104 A sends  548 B an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 , similar to event  548 A. As a result, the UE  102  disconnects  550 B from the SN  106 A and releases the first preferred configuration in response to releasing the SN  106 A, similar to event  550 A. The UE  102  then transmits  552 B an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message, similar to event  552 A. Accordingly, the UE  102  in SC communicates  554 B with the MN  104 A after disconnecting from the SN  106 A, similar to event  554 A. 
     Referring now to  FIG.  5 C , in a scenario  500 C, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  5 A  or  FIG.  5 B  the MN  104 A or the SN  106 A initiates the SN release procedure independent of the first preferred configuration received from the UE  102 , in  FIG.  5 C  the UE  102  informs the SN  106 A to initiate the SN release procedure by way of sending the first preferred configuration to the SN  106 A. 
     Initially, the UE  102  communicates  502 C data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 A. Later in time, the MN  104 A performs a DC configuration procedure  560 C, similar to the DC configuration procedure  560 A. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  560 C. 
     After the UE  102  connects to the SN  106 A, either the MN  104 A or the SN  106 A can initiate  528 C a UE assistance configuration procedure with the UE  102 , similar to event  528 A, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  530 C, similar to events  530 A or  531 B, thereby providing a first preferred configuration to the SN  106 A. In some implementations, the first preferred configuration generated by the UE  102  can include indications for releasing the SN  106 A. For example, if the SN  106 A is a 5G base station such as a gNB, the first preferred configuration includes indications for disabling 5G. As another example, the first preferred configuration includes indications for zero SCells associated with the SN  106 A. For example, the indications can be reducedCCsDL and/or reducedCCsUL fields. In the first preferred configuration or UE assistance information message, the UE  102  can include the reducedCCsDL field having a value “0” to indicate zero SCells associated with the SN  106 A, in one implementation. In this implementation, the UE  102  may or may not include the reducedCCsUL field in the first preferred configuration or UE assistance information message. If the UE  102  includes the reducedCCsUL field, it may have a value “0” or a value other than “0”. If the SN  106 A receives the reducedCCsDL field with value “0” and the reducedCCsUL field with a value other than “0”, the SN  106 A can determine that the UE  102  indicates zero SCells associated with the SN  106 A according to the reducedCCsDL field and ignore the reducedCCsUL field. Upon receiving the first preferred configuration, the SN  106 A, instead of generating a second DU configuration like in events  536 A or  536 B, determines  537 C to perform an SN release procedure in response to the first preferred configuration. 
     Accordingly, the SN  106 A can initiate  546 C the SN release procedure to release the SN  106 A for the UE  102 . After the SN  106 A determines to release the SN  106 A, the MN  104 A sends  548 C an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 , similar to event  548 A. As a result, the UE  102  disconnects  550 C from the SN  106 A and releases the first preferred configuration in response to releasing the SN  106 A, similar to event  550 A. The UE  102  then transmits  552 C an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message, similar to event  552 A. Accordingly, the UE  102  in SC communicates  554 C with the MN  104 A after disconnecting from the SN  106 A, similar to event  554 A. 
     Referring now to  FIG.  5 D , in a scenario  500 D, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  5 A  the UE  102  releases the first preferred configuration at event  550 A, in  FIG.  5 D  the UE  102  retains the first preferred configuration. 
     Initially, the UE  102  communicates  502 D data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 A. Later in time, the MN  104 A performs a DC configuration procedure  560 D, similar to the DC configuration procedure  560 A. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  560 D. 
     After the UE  102  connects to the SN  106 A, whereas in  FIG.  5 A  either the MN  104 A or the SN  106 A can initiate  528 A a UE assistance configuration procedure, in  FIG.  5 D  only the MN  104 A can initiate  528 D the UE assistance configuration procedure, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  530 D by transmitting a UE assistance information message including a first preferred configuration to the SN  106 A via the MN  104 A for different reasons in various scenarios and implementations, as discussed above with respect to  FIG.  5 A . The SN  106 A then generates  536 D a second DU configuration in response to receiving the first preferred configuration, similar to event  536 A. 
     In some implementations, after generating the second DU configuration, the SN  106 A performs an RRC reconfiguration procedure  570 D with the UE  102 , similar to events  570 A or  571 B. Thus, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A during the DC configuration procedure  560 D in the first DU configuration with the second DU configuration, and communicate with the SN  106 A by using the updated configuration parameters. 
     Later in time (e.g., after the MN  104 A or the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the MN  104 A or the SN  106 A can initiate  546 D an SN release procedure to release the SN  106 A for the UE  102 , similar to event  546 A. After either the MN  104 A or the SN  106 A determines to release the SN  106 A, the MN  104 A sends  548 D an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 , similar to event  548 A. As a result, the UE  102  disconnects  550 D from the SN  106 A, similar to event  550 A, but retains the first preferred configuration in response to releasing the SN  106 A. The UE  102  then transmits  552 D an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message, similar to event  552 A. Accordingly, the UE  102  in SC communicates  554 D with the MN  104 A after disconnecting from the SN  106 A, similar to event  554 A. 
     Later in time, the UE  102  can transmit  556 D another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the MN  104 A, similar to the manner in which the UE  102  can transmit  344 B the second preferred configuration to the DU  174  of the base station  104 A discussed above with respect to  FIG.  3 B . By sending the second preferred configuration to the MN  104 A, the UE  102  can override the first preferred configuration retained at the MN  104 A during the UE assistance information procedure  530 D, so that the UE  102  and MN  104 A can then communicate using the second preferred configuration. The MN  104 A can also store  558 D the second preferred configuration. In some implementations, the MN  104 A can release the first preferred configuration at event  558 D. In other implementations, the MN  104 A can store preferred parameter(s) that remain unchanged by the second preferred configuration at event  558 D. 
     The UE  102  can transmit  556 D the second preferred configuration for similar reasons described above with respect to  FIG.  3 B . In one particular example, the UE  102  can transmit the second preferred configuration to adjust (e.g., increase or decrease) the number of SCells associated with the SN  106 A as indicated in the first preferred configuration or release the first preferred configuration. As such, because the MN  104 A can store  558 D the second preferred configuration, the MN  104 A can accommodate preferences of the UE  102  related to the SN  106 A if the MN  104 A later determines to perform a DC configuration procedure, similar to event  560 D. 
     Referring now to  FIG.  5 E , in a scenario  500 E, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  5 C  the UE  102  disconnects from the SN  106 A and releases the first preferred configuration, in  FIG.  5 E  the UE  102  disconnects from the SN  106 A and retains the first preferred configuration. 
     Initially, the UE  102  communicates  502 E data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 C. Later in time, the MN  104 A performs a DC configuration procedure  560 E, similar to the DC configuration procedure  560 C. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  560 E. 
     After the UE  102  connects to the SN  106 A, whereas in  FIG.  5 C  either the MN  104 A or the SN  106 A can initiate  528 C a UE assistance configuration procedure, in  FIG.  5 E  only the MN  104 A can initiate  528 E the UE assistance configuration procedure, similar to event  528 D, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  530 E, similar to event  530 D, thereby providing a first preferred configuration to the SN  106 A. In some implementations, the first preferred configuration generated by the UE  102  can include indications for releasing the SN  106 A. For example, if the SN  106 A is a gNB, the first preferred configuration includes indications for disabling 5G. As another example, the first preferred configuration includes indications (e.g., reducedCCsDL and/or reducedCCsUL fields discussed above) for zero SCells associated with the SN  106 A. Upon receiving the first preferred configuration, the SN  106 A determines  537 E to perform an SN release procedure in response to the first preferred configuration, similar to event  537 C. 
     Accordingly, the SN  106 A can initiate  546 E the SN release procedure to release the SN  106 A for the UE  102 , similar to event  546 C. After the SN  106 A determines to release the SN  106 A, the MN  104 A sends  548 E an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 , similar to event  548 C. As a result, the UE  102  disconnects  550 E from the SN  106 A, similar to event  550 D, but retains the first preferred configuration in response to releasing the SN  106 A. The UE  102  then transmits  552 E an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message, similar to event  552 D. Accordingly, the UE  102  in SC communicates  554 E with the MN  104 A after disconnecting from the SN  106 A, similar to event  554 D. 
     Later in time, the UE  102  can transmit  556 E another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the MN  104 A, similar to event  556 D. By sending the second preferred configuration to the MN  104 A, the UE  102  can override the first preferred configuration retained at the MN  104 A during the UE assistance information procedure  530 E, so that the UE  102  and MN  104 A can then communicate using the second preferred configuration. The UE  102  can transmit  556 E the second preferred configuration for similar reasons described above with respect to  FIG.  5 D . The MN  104 A can also store  558 E the second preferred configuration, similar to event  558 D. 
     Referring now to  FIG.  5 F , in a scenario  500 F, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  5 D  the SN  106 A is capable of receiving a UEAssistanceInformation message including a first preferred configuration from the MN  104 A to generate a second DU configuration at event  536 D, in  FIG.  5 F  the SN  106 A is a legacy base station that is not capable of interpreting a UEAssistanceInformation message. To provide the first preferred configuration to a legacy SN  106 A, the MN  104 A can send the first preferred configuration to the SN  106 A via an SN Modification Request message. 
     Initially, the UE  102  communicates  502 F data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 D. Later in time, the MN  104 A performs a DC configuration procedure  560 F, similar to the DC configuration procedure  560 D. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  560 D. 
     After the UE  102  connects to the SN  106 A, the MN  104 A initiates  528 F the UE assistance configuration procedure to enable the UE  102  to transmit a preferred configuration, similar to event  528 D. After the UE  102  is enabled to transmit a preferred configuration, the UE transmits  532 F a UE assistance information message including a first preferred configuration to the MN  104 , similar to event  532 A. In turn, the MN  104 A translates  533 F the first preferred configuration to an IE that can be readable by the SN  106 A. The IE can be a ConfigRestrictInfoSCG IE as defined in 3 GPP TS 36.331 and 38.331, for example. Subsequently, in contrast to sending the first preferred configuration in a UE assistance information message like in event  534 A, the MN  104 A transmits  535 F an SN Modification Request message including the IE to the SN  106 A. Thus, even if the SN  106 A is a legacy base station that is unable to interpret the UE assistance information message, the SN  106 A can interpret the SN Modification Request message and generate  536 F a second DU configuration in response to receiving the first preferred configuration via the SN Modification Request message. 
     In some implementations, after generating the second DU configuration, the SN  106 A sends  538 F an RRC reconfiguration message including the second DU configuration to the MN  104 A via an SN Modification Request Acknowledge message, which in turn transmits  540 F the RRC reconfiguration message to the UE  102  via an RRC container message. In response, the UE  102  can transmit  542 F an RRC reconfiguration complete message to the MN  104 A via an RRC container response message, which in turn sends  544 F the RRC reconfiguration complete message to the SN  106 A via an SN Reconfiguration Complete message. Thus, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A during the DC configuration procedure  560 F in the first DU configuration with the second DU configuration, and communicate with the SN  106 A by using the updated configuration parameters. The events  528 F,  532 F,  533 F,  535 F,  536 F,  538 F,  540 F,  542 F, and  544 F are collectively referred to in  FIG.  5 F  as a legacy UE assistance information procedure  572 F. 
     Later in time (e.g., after the MN  104 A or the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the MN  104 A or the SN  106 A can initiate  546 F an SN release procedure to release the SN  106 A for the UE  102 , similar to event  546 D. After either the MN  104 A or the SN  106 A determines to release the SN  106 A, the MN  104 A sends  548 F an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 , similar to event  548 D. As a result, the UE  102  disconnects  550 F from the SN  106 A and retains the first preferred configuration in response to releasing the SN  106 A, similar to event  550 D. The UE  102  then transmits  552 F an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message, similar to event  552 D. Accordingly, the UE  102  in SC communicates  554 F with the MN  104 A after disconnecting from the SN  106 A, similar to event  554 D. 
     Later in time, the UE  102  can transmit  556 F another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the MN  104 A, similar to event  556 D, for similar reasons described above with respect to  FIG.  5 D . By sending the second preferred configuration to the MN  104 A, the UE  102  can override the first preferred configuration retained at the MN  104 A during the legacy UE assistance information procedure  572 F, so that the UE  102  and MN  104 A can then communicate using the second preferred configuration. The MN  104 A can store  558 F the second preferred configuration, similar to event  558 D. In doing so, the MN  104 A can accommodate preferences of the UE  102  related to the SN  106 A if the MN  104 A later determines to perform a DC configuration procedure, similar to event  560 F. In some implementations, the MN  104 A can release the first preferred configuration at event  558 F. 
     Later, the MN  104 A can perform a DC configuration procedure with an SN (e.g., SN  106 A or SN  106 B), similar to the DC configuration procedure  560 A. In one implementation, the MN  104 A can translate the second preferred configuration to an IE (e.g., ConfigRestrictInfoSCG IE) that can be readable by the SN, and send an SN Addition Request message including the IE to the SN in the DC configuration procedure. Therefore, the SN can generate a DU configuration according to the IE to satisfy the second preferred configuration for the UE  102 , and transmit the DU configuration to the UE  102  via the MN  104 A, similar to the events  516 A and  517 A. In another implementation, if the MN  104 A releases the first preferred configuration, the MN  104 A can translate the UE capabilities to an IE (e.g., ConfigRestrictInfoSCG IE) that can be readable by the SN, and send an SN Addition Request message including the IE to the SN in the DC configuration procedure. 
     Referring now to  FIG.  5 G , in a scenario  500 G, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  5 E  the SN  106 A determines to perform the SN release procedure at event  537 E, in  FIG.  5 G  the MN  104 A determines to perform the SN release procedure. 
     Initially, the UE  102  communicates  502 G data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 E. Later in time, the MN  104 A performs a DC configuration procedure  560 G, similar to the DC configuration procedure  560 E. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  560 G. 
     After the UE  102  connects to the SN  106 A, the MN  104 A can initiate  528 G the UE assistance configuration procedure, similar to event  528 E, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  transmits  532 G a UE assistance information message including a first preferred configuration to the MN  104 , similar to event  532 A. The first preferred configuration can include an indication to release the SN  106 A or disabling 5G. In turn, the MN  104 A determines  537 G to perform an SN release procedure in response to the first preferred configuration. Subsequently, the MN  104 A sends  539 G an SN Release Request message to the SN  106 A, which in turn sends  547 G an SN Release Request Acknowledge message to the MN  104 A. In turn, the MN  104 A sends  548 G an RRC reconfiguration message indicating release of the SN  106 A to the UE  102 , similar to event  548 E. As a result, the UE  102  disconnects  550 G from the SN  106 A and retains the first preferred configuration in response to releasing the SN  106 A, similar to event  550 E. The UE  102  then transmits  552 G an RRC reconfiguration complete message to the MN  104 A in response to the RRC reconfiguration message, similar to event  552 E. Accordingly, the UE  102  in SC communicates  554 G with the MN  104 A after disconnecting from the SN  106 A, similar to event  554 E. 
     Later in time, the UE  102  can transmit  556 G another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the MN  104 A, similar to event  556 E. For example, the second preferred configuration can include an indication to add the SN  106 A that was previously indicated to be released in the first preferred configuration. By sending the second preferred configuration to the MN  104 A, the UE  102  can override the first preferred configuration retained at the MN  104 A at event  532 G, so that the UE  102  and MN  104 A can then communicate using the second preferred configuration. The UE  102  can transmit  556 G the second preferred configuration for similar reasons described above with respect to  FIG.  5 E . The MN  104 A can store  558 G the second preferred configuration, similar to event  558 E. In doing so, the MN  104 A can perform a DC configuration procedure for the UE  102  or accommodate preferences of the UE  102  related to the SN  106 A if the MN  104 A later determines to perform a DC configuration procedure. In some implementations, the MN  104 A can release the first preferred configuration at event  558 G. 
     Now referring to  FIGS.  6 A- 6 C , the UE  102  retains or releases a preferred configuration in response to suspending a radio connection with the RAN. 
     Referring first to  FIG.  6 A , in a scenario  600 A, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Later, e.g., due to data inactivity between the UE  102  and the SN  106 A, the radio connection between the UE  102  and the SN  106 A is suspended. The UE  102  and the SN  106 A retain the first preferred configuration, and later the UE  102  provides a second preferred configuration to override the retained first preferred configuration upon resuming connectivity with the SN  106 A. 
     Initially, the UE  102  communicates  602 A data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 D. Later in time, the MN  104 A performs a DC configuration procedure  660 A, similar to the DC configuration procedure  560 D. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  660 A. 
     After the UE  102  connects to the SN  106 A, the SN  106 A initiates  628 A the UE assistance configuration procedure, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  630 A, similar to events  530 A or  531 B, by transmitting a UE assistance information message including a first preferred configuration to the SN  106 A, either directly or via the MN  104 A for different reasons in various scenarios and implementations, as discussed above with respect to  FIG.  5 A . The SN  106 A then generates  636 A a second DU configuration in response to receiving the first preferred configuration, similar to event  536 D. 
     In some implementations, after generating the second DU configuration, the SN  106 A performs an RRC reconfiguration procedure  670 A with the UE  102 , similar to event  570 D. Thus, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A during the DC configuration procedure  660 A in the first DU configuration with the second DU configuration, and communicate with the SN  106 A by using the updated configuration parameters. 
     Later in time (e.g., after the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the SN  106 A sends  682 A an Activity Notification message to the MN  104 A, indicating that the traffic of the UE  102  is inactive on some or all of the SN-terminated radio bearer(s). After receiving the Activity Notification message, the MN  104 A determines that the UE  102  should transition to the inactive state. In response to this determination, or in response to receiving the Activity Notification message, the MN  104 A transmits  684 A to the SN  106 A an SN Modification Request message for the UE  102 . The SN Modification Request message includes an indication that the SN  106 A should suspend lower layers of the SN-terminated radio bearer(s). For example, the SN Modification Request message can indicate that the SN  106 A should suspend the resources of the PHY layer, the MAC layer, and/or the RLC layer. In response to receiving the SN Modification Request message, the SN  106 A suspends the lower layers of the SN-terminated radio bearer(s) and transmits  686 A an SN Modification Request Acknowledge message to the MN  104 A. 
     In response to receiving the SN Modification Request Acknowledge message, the MN  104 A performs an RRC suspension procedure  678 A, similar to the RRC suspension procedure  378 A. As a result, the UE  102  suspends the radio connection associated with the SN  106 A, and can transition to an inactive state or an idle state. 
     In some implementations, after the MN  104 A performs the RRC suspension procedure  678 A with the UE  102 , the UE  102  can retain  654 A the first preferred configuration (e.g., in response to receiving an RRC suspension message during the RRC suspension procedure  678 A). Similarly, in some implementations, the SN  106 A can retain  653 A the first preferred configuration. 
     Later in time (e.g., after the SN  106 A detects that traffic of the UE  102  is active on the SN-terminated radio bearer(s)), the SN  106 A can send  688 A an Activity Notification message to the MN  104 A, indicating that the traffic of the UE  102  is active on some or all of the SN-terminated radio bearer(s), in some implementations. In turn, MN  104 A sends  689 A a Paging message to the UE  102 . In response to the Paging message, the UE  102  can transmit  631 A an RRC resume request message to the MN  104 A. In other implementations, the UE  102  can transmit  631 A an RRC resume request message to the MN  104 A upon determining to initiate a data transmission with the SN  106 A instead of in response to the Paging message. 
     In response to receiving either the Activity Notification message from the SN  106 A or the RRC resume request message from the UE  102 , the MN  104 A determines that the UE  102  should transition back to the connected state. In response to this determination, or in response to receiving the Activity Notification message, the MN  104 A transmits  690 A to the SN  106 A an SN Modification Request message for the UE  102 . The SN Modification Request message includes an indication that the SN  106 A should resume the lower layers of the SN-terminated radio bearer(s) that were previously suspended at event  684 A. For example, the SN Modification Request message can indicate that the SN  106 A should resume the resources of the PHY layer, the MAC layer, and/or the RLC layer. In response to receiving the SN Modification Request message, the SN  106 A resumes the lower layers of the SN-terminated radio bearer(s) and transmits  692 A an RRC reconfiguration message to the MN  104 A via an SN Modification Request Acknowledge message to enable the UE  102  to again communicate with the SN  106 A. In turn, the MN  104 A transmits  637 A the RRC reconfiguration message to the UE  102  via an RRC resume message. As a result, the UE  102  resumes  638 A the suspended radio connection and transitions to the connected state. The UE  102  can transmit  640 A an RRC reconfiguration complete message to the MN  104 A via an RRC resume complete message, which in turn can send  694 A an RRC reconfiguration complete message to the SN  106 A via an SN reconfiguration complete message. 
     The UE  102  then initiates  696 A a random access procedure with the SN  106 A, e.g., by using one or more random access configurations included in the RRC reconfiguration message. After gaining access to a channel, the SN  106 A identifies the UE  102  during the random access procedure (e.g., the UE  102  succeeds the contention resolution), and as a result, the UE  102  communicates control signals and data with the SN  106 A. 
     Later in time, the UE  102  can transmit  656 A another UE assistance information message including another preferred configuration (i.e., a second preferred configuration) to the SN  106 A, either directly (not shown) or via the MN  104 A at event  657 A. By sending the second preferred configuration to the SN  106 A, the UE  102  can override the first preferred configuration retained at the SN  106 A at event  653 A, so that the UE  102  and SN  106 A can then communicate using the second preferred configuration. The UE  102  can transmit  656 A the second preferred configuration for similar reasons described above with respect to  FIG.  3 B  and  FIG.  5 D . In one particular example, the UE  102  can transmit the second preferred configuration to adjust (e.g., increase or decrease) the number of SCells associated with the SN  106 A as indicated in the first preferred configuration. 
     Although not shown in  FIG.  6 A , the SN  106 A can proceed to performing a second DU reconfiguration procedure and a second RRC reconfiguration procedure, similar to a second DU reconfiguration procedure  382 B and second RRC reconfiguration procedure  384 B, respectively. Thus, the UE  102  can update the multiple configuration parameters that were previously updated in accordance with the first preferred configuration with a second DU configuration generated during the second DU reconfiguration procedure, and communicate with the SN  106 A by using the updated configuration parameters. 
     Referring now to  FIG.  6 B , in a scenario  600 B, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  6 A  the UE  102  and the SN  106 A retain the first preferred configuration, in  FIG.  6 B  the UE  102  and the SN  106 A release the first preferred configuration. 
     Initially, the UE  102  communicates  602 B data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  602 A. Later in time, the MN  104 A performs a DC configuration procedure  660 B, similar to the DC configuration procedure  660 A. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  660 B. 
     After the UE  102  connects to the SN  106 A, the MN  104 A initiates  628 B the UE assistance configuration procedure, similar to event  528 D, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  630 B, similar to event  530 A, by transmitting a UE assistance information message including a first preferred configuration to the SN  106 A via the MN  104 A for different reasons in various scenarios and implementations, as discussed above with respect to  FIG.  5 A . The SN  106 A then generates  636 B a second DU configuration in response to receiving the first preferred configuration, similar to event  636 A. 
     In some implementations, after generating the second DU configuration, the SN  106 A performs an RRC reconfiguration procedure  670 B with the UE  102 , similar to event  670 A. Thus, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A during the DC configuration procedure  660 B in the first DU configuration with the second DU configuration, and communicate with the SN  106 A by using the updated configuration parameters. 
     Later in time (e.g., after the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the SN  106 A sends  682 B an Activity Notification message to the MN  104 A, similar to event  682 A. The MN  104 A then transmits  684 B to the SN  106 A an SN Modification Request message for the UE  102 , and the SN  106 A in turn transmits  686 B an SN Modification Request Acknowledge message to the MN  104 A, similar to events  684 A and  686 A, respectively. 
     In response to receiving the SN Modification Request Acknowledge message, the MN  104 A performs an RRC suspension procedure  678 B, similar to the RRC suspension procedure  678 A. As a result, the UE  102  suspends the radio connection associated with the SN  106 A, and can transition to an inactive state or an idle state. 
     In some implementations, after the MN  104 A performs the RRC suspension procedure  678 B with the UE  102 , the UE  102  can release  652 B the first preferred configuration (e.g., in response to receiving an RRC suspension message during the RRC suspension procedure  678 B). Similarly, in some implementations, the MN  104 A can optionally release the first preferred configuration at event  651 B, similar to event  351 A. In some implementations, the SN  106 A can release the first preferred configuration at event  653 B as described below. 
     Later in time (e.g., after the SN  106 A detects that traffic of the UE  102  is active on the SN-terminated radio bearer(s)), the SN  106 A can send  688 B an Activity Notification message to the MN  104 A, similar to event  688 A. In turn, MN  104 A sends  689 B a Paging message to the UE  102 , similar to event  689 A. In response to the Paging message, the UE  102  can transmit  631 B an RRC resume request message to the MN  104 A, similar to event  631 A. In other implementations, the UE  102  can transmit  631 B an RRC resume request message to the MN  104 A upon determining to initiate a data transmission with the SN  106 A instead of in response to the Paging message. 
     In response to receiving either the Activity Notification message from the SN  106 A or the RRC resume request message from the UE  102 , the MN  104 A determines that the UE  102  should transition back to the connected state. In response to this determination, or in response to receiving the Activity Notification message, the MN  104 A transmits  690 B to the SN  106 A an SN Modification Request message for the UE  102 , similar to event  690 A. In response to receiving the SN Modification Request message, the SN  106 A resumes the lower layers of the SN-terminated radio bearer(s) and transmits  692 B an RRC reconfiguration message to the MN  104 A via an SN Modification Request Acknowledge message to enable the UE  102  to again communicate with the SN  106 A, similar to event  692 A. In turn, the MN  104 A transmits  637 B the RRC reconfiguration message to the UE  102  via an RRC resume message, similar to event  637 A. As a result, the UE  102  resumes  638 B the suspended radio connection and transitions to the connected state, similar to event  638 A. The UE  102  can then transmit  640 B an RRC reconfiguration complete message to the MN  104 A via an RRC resume complete message, similar to event  640 A, which in turn can send  694 B an RRC reconfiguration complete message to the SN  106 A via an SN reconfiguration complete message, similar to event  694 A. 
     Instead of releasing the first preferred configuration in response to the RRC suspension procedure at event  652 B, the UE  102  can release the first preferred configuration in response to initiating transmission of the RRC resume message or the RRC resume complete message, receiving an RRC resume message, or during the RRC resume procedure, similar to events  352 A and  456 B. 
     In one implementation, the SN  106 A can release  653 B the first preferred configuration after transmitting the Activity Notification message  682 B, after receiving the SN Modification Request message at either event  684 B or event  690 B, after receiving the SN Reconfiguration Complete message at event  694 B, or at any time between any two of events  682 B,  684 B,  686 B,  688 B,  690 B,  692 B,  694 B. 
     The UE  102  then initiates  696 B a random access procedure with the SN  106 A, similar to event  696 A, e.g., by using one or more random access configurations included in the RRC reconfiguration message. After gaining access to a channel, the SN  106 A identifies the UE  102  during the random access procedure (e.g., the UE  102  succeeds the contention resolution), and as a result, the UE  102  communicates control signals and data with the SN  106 A. 
     By releasing the first preferred configuration at the UE  102 , MN  104 A, and SN  106 A at events  652 B,  651 B, and  653 B, respectively, the UE  102 , MN  104 A, and SN  106 A need not be limited to communicating among each other according to the first preferred configuration upon resuming the suspended radio connection. For example, the UE  102  may have recovered from an overheating situation or increased battery power since the inactive state or an idle state, such that the UE  102  is able to utilize more SCell(s), MIMO layer(s), and/or aggregated bandwidth than those indicated in the first preferred configuration after transitioning back to the connected state. 
     Referring now to  FIG.  6 C , in a scenario  600 C, the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . Whereas in  FIG.  6 B  the SN  106 A is capable of receiving a UEAssistanceInformation message including a first preferred configuration from the MN  104 A to generate a second DU configuration at event  636 B, in  FIG.  6 C  the SN  106 A is a legacy base station that is not capable of interpreting a UEAssistanceInformation message. To provide the first preferred configuration to a legacy SN  106 A, the MN  104 A can send the first preferred configuration to the SN  104 A via an SN Modification Request message. 
     Initially, the UE  102  communicates  602 C data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  602 B. Later in time, the MN  104 A performs a DC configuration procedure  660 C, similar to the DC configuration procedure  660 B. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  660 C. 
     After the UE  102  connects to the SN  106 A, the MN  104 A, SN  106 A, and the UE  102  collectively perform a legacy UE assistance information procedure  672 C, similar to the legacy UE assistance information procedure  572 F. In the legacy UE assistance information procedure  672 C, the MN  104 A can translate the first preferred configuration included in a UE assistance information message to an IE (e.g., ConfigRestrictInfoSCG IE) that can be readable by the SN  106 A. Thus, even if the SN  106 A is a legacy base station that is unable to interpret the UE assistance information message, the SN  106 A can interpret the IE and generate a second DU configuration based on the first preferred configuration. Accordingly, the UE  102  can update the multiple configuration parameters previously provided by the SN  106 A during the DC configuration procedure  660 C in the first DU configuration with the second DU configuration, and communicate with the SN  106 A by using the updated configuration parameters 
     Later in time (e.g., after the SN  106 A detects that traffic of the UE  102  is inactive on the SN-terminated radio bearer(s)), the SN  106 A sends  682 C an Activity Notification message to the MN  104 A, similar to event  682 B. The MN  104 A then transmits  684 C to the SN  106 A an SN Modification Request message for the UE  102 , and the SN  106 A in turn transmits  686 C an SN Modification Request Acknowledge message to the MN  104 A, similar to events  684 B and  686 B, respectively. 
     In response to receiving the SN Modification Request Acknowledge message, the MN  104 A performs an RRC suspension procedure  678 C, similar to the RRC suspension procedure  678 B. As a result, the UE  102  suspends the radio connection associated with the SN  106 A, and can transition to an inactive state or an idle state. 
     In some implementations, after the MN  104 A performs the RRC suspension procedure  678 C with the UE  102 , the UE  102  can release  652 C the first preferred configuration (e.g., in response to receiving an RRC suspension message during the RRC suspension procedure  678 C). Similarly, in some implementations, the MN  104 A can release  651 C the first preferred configuration. 
     Later in time (e.g., after the SN  106 A detects that traffic of the UE  102  is active on the SN-terminated radio bearer(s)), the SN  106 A can send  688 C an Activity Notification message to the MN  104 A, similar to event  688 B. In turn, MN  104 A sends  689 C a Paging message to the UE  102 , similar to event  689 B. In response to the Paging message, the UE  102  can transmit  631 C an RRC resume request message to the MN  104 A, similar to event  631 B. In other implementations, the UE  102  can transmit  631 C an RRC resume request message to the MN  104 A upon determining to initiate a data transmission with the SN  106 A instead of in response to the Paging message. 
     In response to receiving either the Activity Notification message from the SN  106 A or the RRC resume request message from the UE  102 , the MN  104 A determines that the UE  102  should transition back to the connected state. In response to this determination, or in response to receiving the Activity Notification message, the MN  104 A transmits  690 C to the SN  106 A an SN Modification Request message for the UE  102 . The SN Modification Request message can include the IE generated by the MN  104 A during the legacy UE assistance information procedure  672 C, or otherwise include a modified IE to adjust (e.g., increase or decrease) the number of SCells associated with the SN  106 A as indicated in the first preferred configuration. In response to receiving the SN Modification Request message, the SN  106 A resumes the lower layers of the SN-terminated radio bearer(s) and transmits  692 C an RRC reconfiguration message to the MN  104 A via an SN Modification Request Acknowledge message to enable the UE  102  to again communicate with the SN  106 A, similar to event  692 B. In turn, the MN  104 A transmits  637 C the RRC reconfiguration message to the UE  102  via an RRC resume message, similar to event  637 B. As a result, the UE  102  resumes  638 C the suspended radio connection and transitions to the connected state, similar to event  638 B. The UE  102  can transmit  640 C an RRC reconfiguration complete message to the MN  104 A via an RRC resume complete message, similar to event  640 B, which in turn can send  694 C an RRC reconfiguration complete message to the SN  106 A via an SN reconfiguration complete message, similar to event  694 B. 
     The UE  102  then initiates  696 C a random access procedure with the SN  106 A, similar to event  696 B. After gaining access to a channel, the SN  106 A identifies the UE  102  during the random access procedure (e.g., the UE  102  succeeds the contention resolution), and as a result, the UE  102  communicates control signals and data with the SN  106 A. 
     By releasing the first preferred configuration at the UE  102  and MN  104 A at events  652 C and  651 C, respectively, the UE  102 , MN  104 A, and SN  106 A need not be limited to communicating among each other according to the first preferred configuration upon resuming the suspended radio connection. For example, the UE  102  may have recovered from an overheating situation or increased battery power since the inactive state or an idle state, such that the UE  102  is able to utilize more SCell(s), MIMO layer(s), and/or aggregated bandwidth than those indicated in the first preferred configuration after transitioning back to the connected state. 
     Referring now to  FIG.  7   , in a PSCell change scenario  700 , the base station  104 A again operates as an MN for the UE  102 , and the base station  106 A again operates as an SN for the UE  102 . In the PSCell change scenario  700 , the SN  106 A (i.e., an S-SN) can forward the first preferred configuration to a T-SN (e.g., T-SN  106 B) via the MN  104 A, so that the SN  106 B can be aware of the first preferred configuration when the UE  102  performs a PSCell change procedure from a PSCell of the S-SN  106 A to a target PSCell of the T-SN  106 B 
     Initially, the UE  102  communicates  702  data in SC with the MN  104 A via cell  124 A by using an MN configuration, similar to event  502 A. Later in time, the MN  104 A performs a DC configuration procedure  760 , similar to the DC configuration procedure  560 A. As a result, the UE  102  communicates control signals and data in DC with the MN  104 A and with the S-SN  106 A by using a first DU configuration received from the MN  104 A during the DC configuration procedure  760 . 
     After the UE  102  connects to the S-SN  106 A, the MN  104 A or the S-SN  106 A initiates  728  the UE assistance configuration procedure, to enable the UE  102  to transmit a preferred configuration. After the UE  102  is enabled to transmit a preferred configuration, the UE  102  performs a UE assistance information procedure  730 , similar to events  530 A or  531 B, by transmitting a UE assistance information message including a first preferred configuration to the S-SN  106 A, either directly or via the MN  104 A for different reasons in various scenarios and implementations, as discussed above with respect to  FIG.  5 A . The S-SN  106 A then generates  736  a second DU configuration in response to receiving the first preferred configuration, similar to event  536 A. 
     In some implementations, after generating the second DU configuration, the S-SN  106 A performs an RRC reconfiguration procedure  770  with the UE  102 , similar to events  570 A or  571 B. Thus, the UE  102  can update the multiple configuration parameters previously provided by the S-SN  106 A during the DC configuration procedure  760  in the first DU configuration with the second DU configuration, and communicate with the S-SN  106 A by using the updated configuration parameters. 
     Later in time, the MN  104 A determines to initiate a PSCell change involving an SN change (i.e., MN-initiated SN addition or change procedure) for the T-SN  106 B and the UE  102  to communicate via a T-PSCell  126 B, e.g., blindly or in response to detecting a suitable event. For example, the determination can occur in response to the MN  104 A receiving one or more measurement results from the UE  102  that are above (or below) one or more predetermined thresholds, or calculating a filtered result (from the measurement result(s)) that is above (or below) a predetermined threshold. In another example, the suitable event can be that the UE  102  is moving toward the T-SN  106 B. In yet another example, the suitable event can be one or more measurement results, generated or obtained by the MN  104 A based on measurements of signals received from the UE  102 , being above (or below) one or more predetermined thresholds. 
     In response to determining to initiate the PSCell change, the MN  104 A sends  740  an SN Addition Request message to the T-SN  106 B. In some implementations, the SN Addition Request message includes the UE capabilities and the first preferred configuration received in events  702  and  738 . In some implementations, if the T-SN  106 B is a legacy base station that is not capable of interpreting the first preferred configuration, the SN Addition Request message can include an IE (e.g., ConfigRestrictInfoSCG IE) that corresponds to a translation of the first preferred configuration. In some implementations, if the MN  104 A did not receive the first preferred configuration in event  730  (e.g., similar to event  531 B), the MN  104 A can receive the first preferred configuration from the S-SN  106 A in an SN message at event  738 . In some implementations, the SN message can be an SN Change Required message, an SN Modification Required message, an SN Modification Request Acknowledge message. In other implementations, the SN  106 A can include the first preferred configuration or the UE assistance information message including the first preferred configuration in a CG-Config IE in the SN message. 
     In response, the T-SN  106 B generates a third DU configuration, and sends  742  the third DU configuration in an RRC reconfiguration message to the MN  104 A via an SN Addition Request Acknowledge message. The T-SN  106 B generates the third DU configuration in response to the first preferred configuration in a manner that would not exceed the capabilities of the UE  102 , e.g., by considering the UE capabilities included in the SN Addition Request message. 
     In response to receiving  742  the SN Addition Request Acknowledge message from the T-SN  106 B, the MN  104 A includes the RRC reconfiguration message in an RRC container message, and transmits  744  the RRC container message to the UE  102 . In some implementations, the RRC container message can include one or more random access configurations needed by the UE  102  to connect to the T-SN  106 B, and in some implementations, includes additional fields, such as a mobility field (e.g., mobilityControlInfoSCG field or a reconfigurationWithSync field), which can include some or all of the random access configurations. 
     In response to receiving  744  the RRC container message, the UE  102  transmits  746  an RRC container response message including an RRC reconfiguration complete message to the MN  104 A. In some implementations, the MN  104 A can send  748  an SN message (e.g., SN Reconfiguration Complete message or SN Confirm message) including the RRC reconfiguration complete message to the T-SN  106 B in response to the RRC container response message. 
     In response to receiving  744  the RRC container message, the UE  102  attempts to perform PSCell change to the T-SN  106 B via T-PSCell  126 B in accordance with the configuration(s) included in the RRC reconfiguration message. In attempting to perform the PSCell change, the UE  102  initiates  750  a random access procedure with the T-SN  106 B via T-PSCell  126 B, e.g., by using one or more random access configurations in the RRC reconfiguration message. After the T-SN  106 B identifies the UE  102  during the random access procedure (e.g., the UE  102  succeeds the contention resolution), the UE  102  communicates  752  in DC with MN  104 A and the T-SN  106 B via T-PSCell  126 B by using configuration(s) in the RRC reconfiguration message included in the RRC container message. Later, the UE  102  can provide a second preferred configuration to the T-SN  106 B to override the first preferred configuration, e.g., in a similar manner as described for event  530 A. The UE  102  can transmit the second preferred configuration for different reasons in various scenarios and implementations as described above. 
     In some scenarios and implementations, the S-SN  106 A receives the first UE preferred configuration and does not provide the first UE preferred configuration to the MN  104 A, so that the MN  104 A cannot provide the first UE preferred configuration to the T-SN  106 B. After the UE  102  successfully performs  752  the random access procedure, the UE  102  can provide a second preferred configuration to the T-SN  106 B, e.g., in a similar manner as described for event  530 A or  531 B. The UE  102  can transmit the second preferred configuration for the same or a different reason as when the UE  102  transmits the first preferred configuration. The second preferred configuration can be the same as or different from the first preferred configuration. 
     In some scenarios and implementations, the UE  102  can receive the RRC reconfiguration message in event  744  while or immediately after transmitting a UE assistance information message to the S-SN  106 A via SRB3 (similar to event  531 B). Before successfully transmitting the UE assistance information message to the S-SN  106 A, the UE  102  may disconnect from the S-SN  106 A and perform  750  the random access procedure on the cell  126 B. In other scenarios and implementations, the UE  102  transmits a UE assistance information message to the MN  104 A (similar to event  532 A) or the S-SN  106 A (similar to event  531 B) after the MN  104 A sends  740  the SN Addition Request message. In such scenarios and implementations, the UE  102  cannot ensure that the T-SN  106 B receives the UE assistance information message from the S-SN  106 A. After the UE  102  successfully performs  752  the random access procedure, the UE  102  can provide a second preferred configuration to the T-SN  106 B, e.g., in a similar manner as described for event  530 A or  531 B. The second preferred configuration can be the same as or different from the first preferred configuration. If the MN  104 A receives a UE assistance information message or the first UE preferred configuration after sending  740  the SN Addition Request message, the MN  104 A can send another SN message (i.e., a second SN message) including the UE assistance information message or the first UE preferred configuration to the T-MN  106 B. More particularly, the UE  102  transmits the UE assistance information message or the first UE preferred configuration to the MN  104 A before transmitting  746  the RRC container message. 
     In some implementations, the UE  102  transmits the second preferred configuration to the T-SN  106 B (similar to event  530 A or  531 B) if the RRC reconfiguration message enables the UE  102  to transmit a preferred configuration or enables the UE  102  to transmit a UE assistance information message. Otherwise the UE  102  disables transmission of a preferred configuration or a UE assistance information message. If the UE  102  transmits the UE assistance information message to the S-SN  106 A via the SRB3 (similar to event  531 B) while or immediately before receiving the RRC reconfiguration message, the UE  102  may retransmit the UE assistance information message (i.e., the first preferred configuration) to the T-SN  106 B. If the UE  102  transmits the UE assistance information message to the S-SN  106 A via the MN  104  while or immediately before receiving the RRC reconfiguration message, the UE  102  may not retransmit the UE assistance information message to the T-SN  106 B. “Immediately” as used in this paragraph can be a short duration such as X second(s) (e.g., X=1 or 0&lt;X&lt;10 such as X=1, 1.1, 1.2 . . . , 2, . . . or 9). 
     In one implementation, if the UE  102  receives a RRC reconfiguration message including a secondary cell group configuration (e.g., secondaryCellGroup) from the S-SN  106 A on SRB3 or via the MN  104 A, and the UE  102  transmitted a UE assistance information message during the last X second (e.g., X=1, 0&lt;X&lt;10 such as X=1, 1.1, 1.2 . . . , 2, . . . or 9), and still configured to transmit a preferred configuration by the RRC reconfiguration message, the UE  102  can re-send the UE assistance information message to the T-SN  106 B (similar to event  530 A or  531 B) after completing the random access procedure. Alternatively, instead of re-sending, the UE  102  can send to the T-SN  106 B another UE assistance information message including similar content as the previously transmitted UE assistance information message. Otherwise, the UE  102  may not re-send the UE assistance information message to the MN  104 A or the T-SN  106 B or send to the MN  104 A or T-SN  106 B another UE assistance information message including similar content as the previously transmitted UE assistance information message, after completing the random access procedure. 
     In another implementation, when the UE  102  receives an RRC reconfiguration message including a secondary cell group configuration (e.g., secondaryCellGroup) from the S-SN  106 A on SRB3 or via the MN  104 A, and if the UE  102  transmitted a UE assistance information message and did not receive from the MN  104 A or the S-SN  106 A an acknowledge message (e.g., an RLC Control PDU, a PDCP Control PDU, or a HARQ acknowledge) for the UE assistance information message, the UE  102  can re-send the UE assistance information message to the T-SN  106 B (similar to event  530 A or  531 B) after completing the random access procedure. Alternatively, instead of re-sending, the UE  102  can send to the T-SN  106 B another UE assistance information message including similar content as the previously transmitted UE assistance information message (similar to event  530 A or  531 B). Otherwise, the UE  102  may not re-send the UE assistance information message to the MN  104 A or the T-SN  106 B or send to the MN  104 A or T-SN  106 B another UE assistance information message including similar content as the previously transmitted UE assistance information message, after completing the random access procedure. 
     Whereas in  FIG.  7    the PSCell change scenario  700  occurs between two base stations (e.g., the base stations  104 A,  106 A) with respect to the UE  102 , the description above can apply to a PSCell change scenario within a single base station (e.g., the base station  106 A) with respect to the UE  102 . Description for the UE  102  and T-SN  106 B can apply to the UE  102  and the S-SN  106 A. For example, the S-SN  106 A can transmit an RRC reconfiguration message to the UE  102  via SRB3 to configure the UE  102  to perform PSCell change from PSCell  126 A to a new PSCell (i.e., a second cell operated by the S-SN  106 A that is not shown in  FIG.  1   ). In response, the UE  102  can transmit an RRC reconfiguration complete message via the SRB3 to the S-SN  106 A. In another example, the S-SN  106 A can transmit an RRC reconfiguration message to the UE  102  via the MN  104 A to configure the UE  102  to perform PSCell change from PSCell  126 A to another cell (not shown in  FIG.  1   ). In response, the UE  102  can transmit an RRC reconfiguration complete message to the S-SN  106 A via the MN  104 A. 
     In some scenarios and implementations, the UE  102  can receive the RRC reconfiguration message while or immediately after transmitting a UE assistance information message to the S-SN  106 A via SRB3 (similar to event  531 B). Before successfully transmitting the UE assistance information message to the S-SN  106 A, the UE  102  may disconnect from the PSCell  126 A and perform the random access procedure on the new PSCell. In such scenarios and implementations, the UE  102  cannot ensure that the S-SN  106 A receives the UE assistance information message from the PSCell  126 A. After the UE  102  successfully performs the random access procedure on the new PSCell, the UE  102  can provide a second preferred configuration to the S-SN  106 A, e.g., in a similar manner as described for event  531 B. The second preferred configuration can be the same as or different from the first preferred configuration. 
     In some implementations, the UE  102  transmits the second preferred configuration to the S-SN  106 A via the new PSCell (similar to event  530 A or  531 B) if the RRC reconfiguration message enables the UE  102  to transmit a preferred configuration or enables the UE  102  to transmit a UE assistance information message. Otherwise the UE  102  disables transmission of a preferred configuration or a UE assistance information message. If the UE  102  transmits the UE assistance information message to the S-SN  106 A via the SRB3 via the PSCell  126 A (similar to event  531 B) while or immediately before receiving the RRC reconfiguration message, the UE  102  may retransmit the UE assistance information message (i.e., the first preferred configuration) to the S-SN  106 A via the new PSCell. If the UE  102  transmits the UE assistance information message to the S-SN  106 A via the MN  104  while or immediately before receiving the RRC reconfiguration message, the UE  102  may not retransmit the UE assistance information message to the S-SN  106 A. As discussed above, “immediately” as used in this paragraph can be a short duration such as X second(s) (e.g., X=1 or 0&lt;X&lt;10 such as X=1, 1.1, 1.2 . . . , 2, . . . or 9). 
     In one implementation, if the UE  102  receives a RRC reconfiguration message including a secondary cell group configuration (e.g., secondaryCellGroup) from the S-SN  106 A on SRB3 or via the MN  104 A, and the UE  102  transmitted a UE assistance information message during the last X second (e.g., X=1 or 0&lt;X&lt;10 such as X=1, 1.1, 1.2 . . . , 2, . . . or 9), and still configured to transmit a preferred configuration by the RRC reconfiguration message, the UE  102  can re-send the UE assistance information message to the S-SN  106 A via the SRB3 on the new PSCell (similar to  531 B) after completing the random access procedure on the new PSCell. Alternatively, instead of re-sending, the UE  102  can send to the S-SN  106 A on the new PSCell another UE assistance information message including similar content as the previously transmitted UE assistance information message. Otherwise, the UE  102  may not re-send the UE assistance information message to the MN  104 A or the S-SN  106 A or send to the MN  104 A or S-SN  106 A another UE assistance information message including similar content as the previously transmitted UE assistance information message, after completing the random access procedure on the new PSCell. 
     In another implementation, when the UE  102  receives an RRC reconfiguration message including a secondary cell group configuration (e.g., secondaryCellGroup) from the S-SN  106 A on SRB3 or via the MN  104 A, if the UE  102  transmitted a UE assistance information message on the SRB3 and did not receive from the S-SN  106 A an acknowledge message (e.g., an RLC Control PDU, a PDCP Control PDU, or a HARQ acknowledge) for the UE assistance information message, the UE  102  can re-send the UE assistance information message to the S-SN  106 A via the SRB3 on the new PSCell (similar to event  531 B) after completing the random access procedure on the new PSCell. Alternatively, instead of re-sending, the UE  102  can send to the S-SN  106 A another UE assistance information message including similar content as the previously transmitted UE assistance information message. Otherwise, the UE  102  may not re-send the UE assistance information message to the MN  104 A or the S-SN  106 A on the new PSCell or send to the MN  104 A or S-SN  106 A on the new PSCell another UE assistance information message including similar content as the previously transmitted UE assistance information message, after completing the random access procedure on the new PSCell. 
     The UE  102  can re-send the UE assistance information message to the S-SN  106 A via the new PSCell (similar to event  530 A or  531 B) after completing the random access procedure with the S-SN  106 A on the new PSCell. Alternatively, instead of re-sending, the UE  102  can send to the S-SN  106 B another UE assistance information message including similar contents as the previously transmitted UE assistance information message. 
       FIG.  8 A  is a flow diagram depicting an example method  800 A, implemented in a UE (e.g., UE  102 ), for releasing a preferred configuration. 
     At block  802 A, the UE transmits a preferred configuration (e.g., in any one of events  372 A,  372 C,  472 B). The UE can transmit the preferred configuration to a base station (e.g., base station  104 A, S-BS  104 B, or SN  106 A either directly or via the MN  104 A), in various implementations. 
     At block  804 A, the UE receives an RRC suspension message and suspends a radio connection in response to the RRC suspension message (e.g., in any one of events  378 A,  378 C,  478 B). 
     At block  806 A, in some implementations, the UE releases the preferred configuration in response to the RRC suspension message (e.g., in any one of events  352 A,  456 B). In other implementations, the UE releases the preferred configuration prior to receiving the RRC suspension message at block  804  A (e.g., in event  356 C). For example, during a UE assistance release procedure, the base station can transmit an RRC message to the UE to instruct the UE to release the first preferred configuration. 
       FIG.  8 B  is a flow diagram depicting an example method  800 B as an alternative to the example method  800 A, implemented in a UE (e.g., UE  102 ), for releasing a preferred configuration. 
     At block  802 B, similar to block  802 A, the UE transmits a preferred configuration (e.g., in any one of events  372 A,  372 C,  472 B). 
     At block  804 B, similar to block  804 A, the UE receives an RRC suspension message and suspends a radio connection in response to the RRC suspension message (e.g., in any one of events  378 A,  378 C,  478 B). 
     At block  806 B, the UE performs an RRC resume procedure to resume the suspended radio connection (e.g., in any one of events  380 A,  380 C,  480 B). The UE may perform the RRC resume procedure in response to determining to initiate a data transmission with the base station, or in response to a Paging message received from the base station, for example. 
     Whereas in block  806 A the UE releases the preferred configuration in response to the RRC suspension message, at block  808 B the UE releases the preferred configuration in response to (or during) the RRC resume procedure. 
       FIG.  9    is a flow diagram depicting an example method  900 , implemented in a UE (e.g., UE  102 ), for retaining a preferred configuration. As such, in contrast to releasing the preferred configuration described above with respect to  FIGS.  8 A and  8 B , the UE and the base station can alternatively retain the preferred configuration, yet override the preferred configuration with another preferred configuration if necessary. 
     At block  902 , similar to block  802 A, the UE transmits a preferred configuration (e.g., in any one of events  372 B,  472 A). The UE can transmit the preferred configuration to a base station (e.g., base station  104 A, S-BS  104 B, or SN  106 A either directly or via the MN  104 A), in various implementations. 
     At block  904 , similar to block  804 A, the UE receives an RRC suspension message and suspends a radio connection in response to the RRC suspension message (e.g., in any one of events  378 B,  478 A). 
     Whereas in block  806 A the UE releases the preferred configuration in response to the RRC suspension message, at block  906  the UE retains the preferred configuration in response to the RRC suspension message (e.g., in any one of events  354 B,  454 A). 
     At block  908 , similar to block  806 B, the UE performs an RRC resume procedure to resume the suspended radio connection (e.g., in any one of events  380 B,  480 A). 
     At block  910 , the UE transmits another (i.e., second) preferred configuration to update the previously transmitted preferred configuration to the base station (e.g., in any one of events  344 B,  444 A). By sending the second preferred configuration to the base station, the UE can override the previously transmitted preferred configuration retained at the base station, so that upon resuming connectivity with the base station, the UE and the base station can then communicate using the second preferred configuration, for example. 
       FIG.  10 A  is a flow diagram depicting an example method  1000 A, implemented in a UE (e.g., UE  102 ), for disconnecting from an SN (e.g., SN  106 A) and releasing a preferred configuration. 
     At block  1002 A, the UE transmits a preferred configuration to the SN (e.g., in any one of events  530 A,  531 B,  530 C). The UE can transmit the preferred configuration to the SN either directly or via an MN (e.g., MN  104 A), in various implementations. 
     At block  1004 A, the UE receives, from the MN, an RRC message (e.g., an RRC reconfiguration message) indicating release of the SN (e.g., in any one of events  548 A,  548 B,  548 C). 
     At block  1006 A, the UE disconnects from the SN and releases the preferred configuration in response to the RRC message (e.g., in any one of events  550 A,  550 B,  550 C). 
       FIG.  10 B  is a flow diagram depicting an example method  1000 B as an alternative to the example method  1000 A, implemented in a UE (e.g., UE  102 ), for disconnecting from an SN (e.g., SN  106 A) and releasing a preferred configuration. 
     At block  1002 B, similar to block  1002 A, the UE transmits a preferred configuration to the SN (e.g., in any one of events  530 A,  531 B,  530 C). 
     At block  1004 B, similar to block  1004 A, the UE receives an RRC message (e.g., an RRC reconfiguration message) indicating release of the SN (e.g., in any one of events  548 A,  548 B,  548 C). 
     Whereas in block  1006 A the UE disconnects from the SN and releases the preferred configuration in response to the RRC message, at block  1006 B, the UE disconnects from the SN but does not yet release the preferred configuration. Instead, the UE at block  1008 B receives another (i.e., second) RRC message (e.g., an RRC resume message) indicating addition of the SN (e.g., the same SN  106 A or a different SN than the SN  106 A) and subsequently at block  1010 B releases the preferred configuration in response to the second RRC message. 
       FIG.  11    is a flow diagram depicting an example method  1100 , implemented in a UE (e.g., UE  102 ), for disconnecting from an SN (e.g., SN  106 A) and retaining a preferred configuration. As such, in contrast to releasing the preferred configuration described above with respect to  FIGS.  10 A and  10 B , the UE and the base station can alternatively retain the preferred configuration, yet override the preferred configuration with another preferred configuration if necessary. 
     At block  1102 , similar to block  1002 A, the UE transmits a preferred configuration to the SN (e.g., in event  630 A). 
     At block  1104 , similar to block  1004 A, the UE receives, from the MN, a first RRC message (e.g., an RRC reconfiguration message) indicating release of the SN (e.g., in event  678 A). 
     Whereas in block  1006 A the UE disconnects from the SN and releases the preferred configuration in response to the first RRC message, at block  1106  the UE disconnects from the SN and retains the preferred configuration in response to the first RRC message (e.g., in event  654 A). 
     At block  1108 , the UE receives a second RRC message (e.g., an RRC resume message) indicating addition of the SN (e.g., the same SN  106 A or a different SN than the SN  106 A) (e.g., in event  637 A). 
     At block  1110 , the UE transmits another (i.e., second) preferred configuration to the SN to update the previously transmitted preferred configuration in response to the second RRC message (e.g., in event  656 A). By sending the second preferred configuration to the SN, the UE can override the previously transmitted preferred configuration retained at the SN, so that upon resuming connectivity with the SN, the UE and the SN can then communicate using the second preferred configuration, for example. 
       FIG.  12 A  is a flow diagram depicting an example method  1200 A, implemented in an MN (e.g., MN  104 A), for determining whether to perform a UE assistance configuration procedure to enable the UE (e.g., UE  102 ) to transmit a preferred configuration to an SN (e.g., SN  106 A). 
     At block  1202 A, the MN receives UE capabilities of the UE. In various implementations, the MN can receive UE capabilities from the UE, the CN (e.g., CN  110 ), or another base station (e.g., base station  104 B). 
     At block  1204 A, the MN determines whether the UE capabilities indicate that the UE supports transmitting a preferred configuration. If at block  1204 A the MN determines that the UE capabilities indicate that the UE is not capable of transmitting a preferred configuration, the MN at block  1210 A does not perform a UE assistance configuration procedure. 
     If at block  1204 A the MN determines that the UE capabilities indicate that the UE is capable of transmitting a preferred configuration, the MN at block  1206 A determines whether the SN is capable of processing the preferred configuration. For example, the MN may be preconfigured to be aware of the capabilities of the SN. In yet another example, the MN may be can be informed by a network node (e.g., an operation and maintenance (Q&amp;M) node) as to the capabilities of the SN. 
     If at block  1206 A the MN determines that the SN is not capable of processing the preferred configuration, the MN at block  1210 A does not perform a UE assistance configuration procedure. If at block  1206 A the MN determines that the SN is capable of processing the preferred configuration, the MN at block  1208 A performs the UE assistance configuration procedure (e.g., in any one of events  528 A,  528 B,  528 C,  528 D,  528 E,  528 F,  528 G,  628 A,  628 B,  672 C,  728 ). In the UE assistance configuration procedure, the MN can transmit an RRC message to the UE, enabling the UE to transmit the preferred configuration to the SN. 
       FIG.  12 B  is a flow diagram depicting an example method  1200 B, implemented in an MN (e.g., MN  104 A), for determining whether to transmit a preferred configuration to an SN (e.g., SN  106 A). 
     At block  1202 B, the MN receives a UE preferred configuration (e.g., in any one of events  530 A,  530 C,  530 D,  530 E,  630 A,  630 B,  672 C,  730 ). The MN may receive the UE preferred configuration from the UE via a UE assistance information message, for example. 
     At block  1204 B, similar to block  1206 A, the MN determines whether the SN is capable of processing the UE preferred configuration. 
     If at block  1204 B the MN determines that the SN is not capable of processing the preferred configuration, the MN at block  1208 B does not transmit the preferred configuration to the SN. If at block  1204 B the MN determines that the SN is capable of processing the preferred configuration, the MN at block  1206 B transmits the preferred configuration to the SN (e.g., in any one of events  530 A,  530 C,  530 D,  530 E,  630 A,  630 B,  730 ). 
       FIG.  12 C  is a flow diagram depicting an example method  1200 C, implemented in an SN (e.g., SN  106 A), for determining whether to act upon a UE preferred configuration received from an MN (e.g., MN  104 A). 
     At block  1202 C, the SN receives a UE preferred configuration from the MN (e.g., in any one of events  530 A,  530 D,  630 A,  630 B,  730 ). 
     At block  1204 C, the SN determines whether it is capable of processing the UE preferred configuration. For example, if the SN is unable to comprehend the UE preferred configuration, or comprehends the UE preferred configuration but cannot generate a DU configuration in response to receiving the UE preferred configuration, the SN determines that it is unable to process the UE preferred configuration. 
     If at block  1204 C the SN determines that it is not capable of processing the UE preferred configuration, the SN at block  1208 C ignores the UE preferred configuration. In some implementations, the SN does not transmit an error message back to the MN indicating that the SN is unable to process the UE preferred configuration. For example, the SN may transmit an SN Addition Request Acknowledge message to the MN rather than sending an SN Addition Reject message. 
     If at block  1204 C the SN determines that it is capable of processing the UE preferred configuration, the SN at block  1206 C generates a DU configuration according to the UE preferred configuration (e.g., in any one of events  536 A,  536 D,  636 A,  636 B,  736 ). 
       FIG.  13    is a flow diagram depicting an example method  1300 , implemented in a distributed SN (e.g., SN  106 A), for handling a UE preferred configuration received from an MN (e.g., MN  104 A) within the distributed SN. 
     At block  1302 , a CU of the distributed SN receives a UE preferred configuration from the MN (e.g., in any one of events  530 A,  530 D,  630 A,  630 B,  730 ). 
     At block  1304 , the CU sends the UE preferred configuration to a DU (e.g., in any one of events  536 A,  536 D,  636 A,  636 B,  736 ). 
     At block  1306 , the CU receives a DU configuration from the DU in response to the UE preferred configuration (e.g., in any one of events  536 A,  536 D,  636 A,  636 B,  736 ). 
       FIG.  14 A  is a flow diagram depicting an example method  1400 A, implemented in an MN (e.g., MN  104 A), for analyzing a UE preferred configuration. 
     At block  1402 A, the MN receives a UE preferred configuration (e.g., in event  532 F). The MN may receive the UE preferred configuration from the UE (e.g., UE  102 ) via a UE assistance information message, for example. 
     At block  1404 A, the MN determines whether a reducedCCsDL IE in the UE preferred configuration is set to 0. The reducedCCsDL IE indicates the number of maximum SCells the UE prefers to be temporarily configured in downlink communications with an SN (e.g., SN  106 A). Thus, if the reducedCCsDL IE is set to 0 in the UE preferred configuration, the UE is indicating that it does not prefer to connect to the SN. 
     If at block  1404 A the MN determines that the reducedCCsDL IE is set to 0, the MN at block  1406 A sends an SN Release Request message to the SN to release the SN. If at block  1404 A the MN determines that the reducedCCsDL IE is not set to 0, the MN at block  1408 A generates a ConfigRestrictInfoSCG IE from the UE preferred configuration and sends the ConfigRestrictInfoSCG IE (e.g., in an SN Modification Request message) to the SN (e.g., in events  533 F,  535 F). Thus, even if the SN is a legacy base station that is unable to interpret a UE assistance information message that includes the UE preferred configuration, the SN can interpret the SN Modification Request message to read the UE preferred configuration. 
       FIG.  14 B  is a flow diagram depicting an example method  1400 B, implemented in an SN (e.g., SN  106 A), for analyzing a UE preferred configuration. 
     At block  1402 B, the SN receives a UE preferred configuration from an MN (e.g., MN  104 A) (e.g., in any one of events  530 A,  530 C,  530 D,  530 E,  535 F,  630 A,  630 B,  730 ). 
     At block  1404 B, the SN determines whether a reducedCCsDL IE in the UE preferred configuration is set to 0. 
     If at block  1404 B the SN determines that the reducedCCsDL IE is set to 0, the SN at block  1406 B sends an SN Release Required message to the MN to require the MN to release the SN (e.g., in event  546 C,  546 E). If at block  1404 B the SN determines that the reducedCCsDL IE is not set to 0, the SN at block  1408 B generates a DU configuration according to the preferred configuration (e.g., in any one of events  536 A,  536 D,  536 F,  636 A,  636 B,  736 ) and transmits the DU configuration to the UE directly or via the MN (e.g., in any one of events  570 A,  570 D,  538 F,  670 A,  670 B,  770 ). 
     Next,  FIG.  15    illustrates an example method  1500  for managing a preferred configuration, which can be implemented in a suitable UE such as the UE  102 . At block  1502 , the UE transmits a preferred configuration to a base station in the RAN, as discussed with reference to blocks  802 A,  802 B, or  902 , for example. At block  1504 , the UE transitions to a state in which a radio connection between the UE and the RAN is suspended, e.g., RRC INACTIVE (e.g., blocks  806 A,  806 B, or  906 ). At block  1506 , the UE releases the preferred configuration, prior to communicating data over the radio connection (e.g., blocks  806 A,  810 B,  910 ). 
     Next,  FIG.  16    illustrates an example method  1600  for managing a preferred configuration, which can be implemented in a suitable UE such as the UE  102 . 
     At block  1602 , the UE in DC communicates with a MN and a SN (e.g., in events  560 A). 
     Then the UE at block  1604  in DC transmits a UE assistance information message to the SN in the RAN (e.g., in any of events  530 A,  531 B). 
     At block  1606 , the UE receives an RRC message including mobility information for SCG while or after transmitting the UE assistance information message (e.g., in event  744 ). 
     At block  1608 , the UE performs a mobility operation in response to the RRC message (i.e., according to the mobility information) (e.g., in event  750 ). 
     The UE at block  1610  determines whether the RRC message enables transmission of a UE assistance information message. If the UE at block  1610  determines the RRC message disables transmission of a UE assistance information message, the UE at block  1612  disables transmission of a UE assistance information message in response to the RRC message. If the UE at block  1610  determines the RRC message enables transmission of a UE assistance information message, the UE at block  1614  determines the UE assistance information message was (being) transmitted to the SN via the MN (i.e., via SRB1) or SRB3. If the UE assistance information message was (being) transmitted to the SN via the SRB3, the UE at block  1616  retransmits the UE assistance information message to the SN. If the UE assistance information message was (being) transmitted to the SN via the MN (i.e., via SRB1), the UE at block  1618  refrains from retransmitting the UE assistance information message to the SN. 
     In some implementation, the mobility information for SCG can be a secondary cell group configuration (e.g., secondaryCellGroup) in the RRC message or a ReconfiguraitonWithSync IE included in the secondary cell group configuration in the RRC message. The mobility operation can be a PSCell change or an SN change. 
     The following description may be applied to the description above. 
     A user device in which the techniques of this disclosure can be implemented (e.g., the UE  102 ) can be any suitable device capable of wireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a health monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router. Further, the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS). Still further, the user device can operate as an internet-of-things (IoT) device or a mobile-internet device (MID). Depending on the type, the user device can include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc. 
     Certain embodiments are described in this disclosure as including logic or a number of components or modules. Modules may can be software modules (e.g., code, or machine-readable instructions stored on non-transitory machine-readable medium) or hardware modules. A hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module can comprise dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform certain operations. A hardware module may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations. 
     When implemented in software, the techniques can be provided as part of the operating system, a library used by multiple applications, a particular software application, etc. The software can be executed by one or more general-purpose processors or one or more special-purpose processors. 
     Example 1. A method in a user equipment (UE) for managing a preferred configuration indicative of a maximum allocation preferred by the UE for at least one resource, the method comprising: transmitting, by processing hardware, the preferred configuration to a radio access network (RAN); transitioning, by the processing hardware, to a state in which a radio connection between the UE and the RAN is suspended; and releasing, by the processing hardware, the preferred configuration, prior to communicating data over the radio connection. 
     Example 2. The method of example 1, wherein the releasing is in response to receiving an indication from the RAN that the radio connection is suspended. 
     Example 3. The method of example 1, further comprising retaining the preferred configuration in response to the indication from the RAN that the radio connection is suspended; and wherein the releasing is in response to receiving an indication from the RAN that the radio connection is resumed. 
     Example 4. The method of example 3, wherein: the indication that the radio connection is suspended is received from a source base station; and the indication that the radio connection is resumed is received from a target base station. 
     Example 5. The method of example 1, further comprising: transmitting, by the processing hardware, a new preferred configuration to the RAN, wherein the releasing is in response to generating the new preferred configuration. 
     Example 6. The method of example 5, wherein: the preferred configuration is transmitted to a source base station; and the new preferred configuration is transmitted to a target base station. 
     Example 7. The method of example 1, wherein the releasing is in response to a command from the RAN to release the preferred configuration. 
     Example 8. The method of example 7, wherein: the UE operates in dual connectivity (DC) with a master node (MN) and a secondary node (SN), and the command to release the preferred configuration is received from the MN. 
     Example 9. The method of any of the preceding examples, wherein the preferred configuration indicates at least one of: (i) a maximum number of secondary cells (SCells), (ii) a maximum number of Multiple Input Multiple Output (MIMO) layers, or (iii) a maximum aggregated bandwidth. 
     Example 10. The method of any of the preceding examples, further comprising: generating, by the processing hardware, the preferred configuration in response to detecting overheating. 
     Example 11. A method in a distributed unit (DU) of a disaggregated base station that includes the DU and a central unit (CU), the method comprising: receiving, by processing hardware from the CU, a preferred configuration indicative of a maximum allocation preferred by a UE for at least one resource; generating, by the processing hardware and using the preferred configuration, a DU configuration for the UE; and transmitting, by the processing hardware to the CU, the DU configuration. 
     Example 12. The method of example 11, wherein: the disaggregated base station is a master node (MN), and the UE operates in dual connectivity (DC) with the MN and a secondary node (SN). 
     Example 13. The method of example 11, wherein the UE performs a handover procedure in which the disaggregated base station is a source base station. 
     Example 14. The method of example 11, wherein the UE performs a handover procedure in which the disaggregated base station is a target base station. 
     Example 15. The method of example 14, wherein: receiving the preferred configuration includes receiving a request to set up a context for the UE. 
     Example 16. The method of example 15, wherein: the preferred configuration is a first preferred configuration; the method further comprising: receiving, from the UE, a second preferred configuration. 
     Example 17. The method of example 16, wherein the second preferred configuration is received in a message that specifies UE assistance information. 
     Example 18. The method of example 16, further comprising: transmitting, by the processing hardware to the UE, a request to resume a previously suspended radio connection; wherein the second preferred configuration is received in response to transmitting the request. 
     Example 19. A method in a central unit (CU) of a disaggregated base station that includes the CU and a distributed unit (DU), the method comprising: receiving, by processing hardware, a preferred configuration indicative of a maximum allocation preferred by a UE for at least one resource; and transmitting, by the processing hardware to the DU, an indication of the maximum allocation preferred by the UE. 
     Example 20. The method of example 19, including receiving the preferred configuration from the UE via a radio interface. 
     Example 21. The method of example 20, wherein the preferred configuration is received in a message specifying UE assistance information. 
     Example 22. The method of example 19, including receiving the preferred configuration from a source base station, wherein the disaggregated base station operates as a target base station during a handover procedure. 
     Example 23. The method of example 22, further comprising: transmitting, to the source base station, a request to retrieve a context for the UE; and wherein the preferred configuration is received in a response to the request. 
     Example 24. The method of example 19, further comprising: receiving, from the DU, a conditional DU configuration that satisfies the maximum allocation preferred by the UE; and transmitting the conditional DU configuration to the UE, wherein the UE connects to the DU in accordance with the conditional DU configuration when one or more conditions for connecting to the DU are satisfied. 
     Example 25. The method of example 19, further comprising: transmitting, to the UE prior to receiving the preferred configuration, a conditional configuration, wherein the UE connects to the disaggregated base station in accordance with the conditional configuration when one or more conditions for connecting to the disaggregated base station are satisfied; and in response to determining that the conditional configuration does not satisfy the preferred configuration, releasing the preferred configuration. 
     Example 26. The method of example 19, further comprising: transmitting, to the UE prior to receiving the preferred configuration, a conditional DU configuration, wherein the UE connects to the DU in accordance with the conditional DU configuration when one or more conditions for connecting to the DU are satisfied; in response to determining that the conditional configuration does not satisfy the preferred configuration, generating a new conditional DU configuration that satisfies the preferred configuration; and transmitting the new conditional DU configuration to the UE. 
     Example 27. The method of example 19, further comprising: transmitting, to the UE prior to receiving the preferred configuration, a conditional DU configuration, wherein the UE connects to the DU in accordance with the conditional DU configuration when one or more conditions for connecting to the DU are satisfied; in response to determining that the conditional configuration does not satisfy the preferred configuration, retaining the preferred configuration; and applying the preferred configuration in response to the UE connecting to the DU. 
     Example 28. A method in master node (MN) for managing configuration of a secondary node (SN) when the UE operates in dual connectivity (DC) with the MN and the SN, the method comprising: determining, by processing hardware and using a capability of at least one of the UE or the SN, whether the SN is to receive an indication of a maximum allocation preferred by the UE for at least one resource; and in response to determining that the SN is to receive the indication, causing the indication to be provided to the SN. 
     Example 29. The method of example 28, wherein the causing includes: receiving, by the processing hardware, a preferred configuration information element (IE) from the UE, the preferred configuration IE including the indication; and transmitting, by the processing hardware, the indication to the SN. 
     Example 30. The method of example 29, wherein transmitting the indication includes forwarding the preferred configuration IE to the SN. 
     Example 31. The method of example 30, wherein the determining includes: determining that the SN supports the preferred configuration IE. 
     Example 32. The method of example 29, wherein transmitting the indication includes: generating a second IE of a type other than the preferred configuration IE; including the indication in the second IE; and transmitting, by the processing hardware, the second IE to the SN. 
     Example 33. The method of example 29, further comprising: determining, by the processing hardware, that the SN is a legacy base station that does not support the preferred configuration IE. 
     Example 34. The method of example 29, wherein the causing includes: transmitting, by the processing hardware to the UE, an indication that the UE is to transmit the indication to the SN via a radio interface between the UE and the SN. 
     Example 35. The method of example 34, wherein the determining includes: using the capability of the UE to determine that the UE is capable of transmitting a preferred UE to the SN, the preferred configuration IE including the indication. 
     Example 36. The method of example 34, wherein the determining includes: using the capability of the SN to determine that the SN supports the preferred configuration IE. 
     Example 37. The method of example 28, further comprising: in a second instance, in response to determining that the SN is to not receive the indication: transmitting, by the processing hardware to the SN, a request to release the SN from the DC. 
     Example 38. A method in a user equipment (UE) for managing a preferred configuration indicative of a maximum allocation preferred by the UE for at least one resource, the UE operating in dual connectivity (DC) with a master node (MN) and a secondary node (SN), the method comprising: transmitting, by processing hardware, the preferred configuration to the MN or the SN; receiving, by the processing hardware, an indication that the SN is released; disconnecting from the SN in response to the indication; and releasing, by the processing hardware, the preferred configuration. 
     Example 39. The method of example 38, wherein the releasing is in response to a command to reconfigure a radio connection, the command including the indication that the SN is released. 
     Example 40. The method of example 38, wherein the preferred configuration is transmitted to the MN. 
     Example 41. The method of example 38, wherein the preferred configuration is transmitted to the SN. 
     Example 42. The method of example 38, further comprising: retaining, by the processing hardware, the preferred configuration in response to the indication that the SN is released; and releasing the preferred configuration in response to generating a new preferred configuration. 
     Example 43. The method of example 42, further comprising: transmitting, by the processing hardware, the new preferred configuration to the MN. 
     Example 44. The method of example 43, wherein the new preferred configuration is transmitted in a UE assistance information message. 
     Example 45. The method of example 38, wherein: the SN is a first SN, and the preferred configuration is a first preferred configuration; the method further comprising: receiving, by the processing hardware and from the MN, mobility information for a secondary cell group (SCG) of a second SN during or after transmitting the first preferred configuration; and determining whether to transmit a second preferred configuration to the first SN or the second SN based on the mobility information. 
     Example 46. The method of example 45, further comprising: enabling direct transmission of the second preferred configuration to the first SN or the second SN, in accordance with the mobility information. 
     Example 47. The method of example 45, further comprising: disabling direct transmission of the second preferred configuration to the first SN or the second SN, in accordance with the mobility information. 
     Example 48. The method of any one of examples 45 to 47, wherein the second preferred configuration is identical to the first preferred configuration. 
     Example 49. A user equipment (UE) comprising processing hardware and configured to implement the method of any of examples 1-10 or 38-48. 
     Example 50. A base station comprising processing hardware and configured to implement the method of any of examples 11-37.