Patent Description:
This application generally relates to wireless communications.

Mobile communications using wireless communication continue to evolve. A fifth generation may be referred to as <NUM>. A previous (legacy) generation of mobile communication may be, for example, fourth generation (<NUM>) long term evolution (LTE).

<CIT> discloses a method and an apparatus for transmitting and receiving measurement information in a mobile communication system. <CIT> discloses that a terminal transmits a connection request message to a network and reports to the network, connection failure-related measurement information when a registered public land mobile network (RPLMN) included in a connection setup message received from the network corresponds to a pre-stored and selected public land mobile network (PLMN) and the connection failure-related measurement information stored with the selected PLMN is available.

<NPL>", provides an overview and overall description of the minimization of drive tests functionality and describes functions and procedures to support collection of UE-specific measurements for MDT using Control Plane architecture, for both UTRAN and E-UTRAN.

A wireless transmit receive unit, WTRU, comprising: a processor configured to:receive a configuration information during a procedure for transitioning the WTRU from a connected state to an inactive state, wherein in the inactive state the WTRU is configured to maintain an access stratum, AS, context, and the configuration information indicates a list of cells on which to perform a measurement based on the WTRU being in the inactive state;perform a measurement on a cell from the list of cells while the WTRU is associated with the inactive state, wherein the cell corresponds to a cell that is supportable by the WTRU as a secondary cell if the WTRU transitioned to the connected state; and perform a resume procedure, wherein performing the resume procedure comprises transitioning from the inactive state to the connected state, and transmitting a result of the measurement to a base station during the transition from the inactive state to the connected state.

A method performed by a wireless transmit receive unit, WTRU, the method comprising: receiving a configuration information during a procedure for transitioning the WTRU from a connected state to an inactive state, wherein in the inactive state the WTRU is configured to maintain an access stratum, AS, context, and the configuration information indicates a list of cells on which to perform a respective measurement based on the WTRU being in the inactive state; performing a measurement on the cell from the list of cells while the WTRU is associated with the inactive state, wherein the cell corresponds to a cell that is supportable by the WTRU as a secondary cell if the WTRU transitioned to the connected state; and performing a resume procedure, wherein performing the resume procedure comprises transitioning from the inactive state to the connected state, and transmitting a result of the measurement to a base station during the transition from the inactive state to the connected state.

Like reference numerals in the figures indicate like elements.

A detailed description of illustrative embodiments will now be described with reference to the various Figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

Table <NUM> is a list of acronyms that me be used herein.

The full duplex radio may include an interference management unit <NUM> to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor <NUM>).

While each of the foregoing elements is depicted as part of the CN <NUM>, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

In view of <FIG>, and the corresponding description of <FIG>, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME <NUM>, SGW <NUM>, PGW <NUM>, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown).

Examples provided herein do not limit applicability of the subject matter to other wireless technologies, e.g., using the same or different principles as may be applicable.

Network may refer to one or more gNBs that may be associated with one or more Transmission/Reception Points (TRPs) or other nodes in a radio access network (RAN).

A RRC state (e.g., RRC_INACTIVE) may be present in NR and/or other radio access technology types. A RRC_INACTIVE state may be characterized, for example, by the one or more of the following: cell re-selection mobility; a CN - NR RAN connection (e.g., both C/U-planes) established for a WTRU; a WTRU's access stratum (AS) context may be stored in at least one gNB and the WTRU; paging may be initiated by an NR RAN; a RAN-based notification area may be managed by an NR RAN; and/or an NR RAN may be aware of a RAN-based notification area that a WTRU belongs to.

Signaling of a transition between a RRC_INACTIVE state and a RRC_CONNECTED state may, for example, include the WTRU sending and/or receiving RRC messages that indicate that an RRC connection should be resumed. Suspend-resume signaling for cellular internet of things (CloT) (e.g., in LTE), where a context may be maintained during a suspend procedure may utilize similar resume signaling.

Dual Connectivity (DC) operation may be supported by a WTRU (e.g., in LTE and/or in NR).

A DC WTRU in a RRC_CONNECTED state may be configured (e.g., in LTE) to utilize the radio resources provided by multiple (e.g., two) distinct schedulers, which may be distinctly located in multiple (e.g., two) eNBs/gNBs that are connected (e.g., via a backhaul over the X2 interface). eNBs involved in DC for a WTRU may assume multiple (e.g., two) different roles. An eNB may, for example, act as a master eNB (MeNB)/master gNB (MgNB) or as a secondary eNB (SeNB)/secondary gNB (SgNB). A WTRU (e.g., in DC) may be connected to the MeNB and/or the SeNB. A WTRU configured with DC may or may not (e.g., in relation to a suspend/resume procedure) release a secondary cell group (SCG) configuration, for example, when resuming a RRC connection (e.g., when a WTRU transitions to a RRC_CONNECTED state).

DC between multiple gNBs may be supported (e.g., in NR). Multi-RAT DC (MR-DC) between a master node (MN) and a secondary node (SN) may be supported (e.g., in NR). MR-DC may take one or more of the following forms: E-UTRA-NR Dual Connectivity (EN-DC), where an MN may be LTE, an SN may be NR and a core network (CN) may be LTE; NG-RAN E-UTRA-NR Dual Connectivity (NGEN-DC), where the LTE CN is replaced with an NR CN; and NR-E-UTRA Dual Connectivity (NE-DC), where an MN may be NR, an SN may be LTE and a CN may be NR.

A WTRU may transition (e.g., transition often) between a RRC_INACTIVE state and a RRC_CONNECTED state (e.g., in NR). If reconfiguration of a DC configuration is performed after each state transition (e.g. each state transition), a WTRU configured with DC may incur a relatively large amount of signaling overhead to in addition to network (NW) signaling to tear down and/or re-establish a CN-RAN connection to an SN. Techniques described herein may allow for a WTRU to transition from the RRC_INACTIVE state to and from the RRC_CONNECTED state with reduced signaling overhead.

A WTRU and/or NW may evaluate the validity of a DC configuration (e.g., a current DC configuration) considering the WTRU's mobility. The WTRU may perform maintenance of valid configurations.

Maintaining a CN-RAN interface with an SN may be implemented, for example, by transferring data on an SCG bearer to a WTRU or NW with minimal signaling/latency for reconfiguration. A NW may (e.g., additionally) be informed, for example, when a CN-RAN interface is switched (e.g., due to WTRU mobility).

A WTRU may be configured to perform DC while in an inactive state (e.g., the RRC_INACTIVE state). A WTRU may perform mobility, for example, while in an inactive state.

A WTRU may maintain an accurate/applicable DC configuration of one or more cells while in the RRC_INACTIVE state. A WTRU performs measurements (e.g., RRM) of connected SN cells and/or neighbor cells (e.g., when a change of cell or SN node may be required). A WTRU may, for example, acquire (e.g., be enabled to acquire) the configuration of a PSCell while in the RRC_INACTIVE state.

A WTRU receives a SI message while in the RRC_INACTIVE state. The WTRU uses the SI message to perform DC while in the RRC_INACTIVE state.

As described herein, a WTRU receives one or more SI message, which uses to perform DC wile in the RRC_INACTIVE state. The quantity and/or size of the SI message received by the WTRU may be reduced. SI for a WTRU may be used for operation/maintenance of DC while the WTRU is in the RRC_INACTIVE state (e.g., DC_Inactive_SI). SI may be transmitted in one or more system information blocks (SIBs)/SI messages, which may be dedicated for that purpose. An SIB or SI message may be broadcasted (e.g., periodically broadcasted) by a cell, which may (e.g., for a given WTRU) be configured as a primary secondary cell (PSCell). In an example, a network may cease (e.g., turn off) broadcasting on a SIB/SI, for example, when there are not any WTRUs currently configured in DC with a given PSCell or surrounding PSCells. An SI message may (e.g., may alternatively) be transmitted by a primary cell (PCell), e.g., as part of PCell's own system information. The contents of an SI message includes, for example, one or more of the following: parameters that are associated with selection/reselection of SN (e.g., thresholds); parameters used to perform measurements of a PSCell (e.g., cell bandwidth, configuration of RSs, measurement configuration, event configuration specific to INACTIVE state, etc.); parameters associated with transmission of data and/or RRC signaling (e.g., directly) to an SN while in the RRC_INACTIVE state (e.g., conditions on WTRU, thresholds, etc.); L1/L2 configuration for PSCells; and/or potential PSCells that may be associated with a PCell, or with a PSCell that may be configured at the time of transition to the RRC_INACTIVE state.

A WTRU receives certain SI, which may be used by the WTRU to perform measurements and/or cell reselection determinations. For example, a WTRU receives a DC_Inactive_SI, which are used by the WTRU to perform measurements and PSCell reselection determinations. The DC_Inactive_SI may include information that allows a WTRU to access a PSCell while the WTRU is in the RRC_INACTIVE state. For example, the DC_Inactive_SI may include random-access channel (RACH) parameters.

A WTRU may receive SI (e.g., DC_Inactive_SI) an MN that is associated with an SN.

A WTRU may request, receive and/or read SI (e.g., DC_Inactive_SI) from an MN. A WTRU may request SI, for example, by using an on-demand request procedure. If a WTRU requests SI using an on-demand request procedure the broadcasting (e.g., at all times) of such information by a cell may be avoided. A WTRU may obtain validity information and/or scheduling information for receiving SI from a MN's minimum SI (e.g., as with any other SI). A WTRU may request SI that is specific to a PSCell and/or a PCell, for example, by including a PSCell/PCell cell ID in an on-demand request. The WTRU may include the PSCell ID in a MSG3 of the SI request, for example, in order to receive system information for the SN PSCell. The WTRU may select a PRACH time/frequency resource and/or preamble associated with the PSCell (e.g., based on the configuration). The WTRU may transmit a PSCell ID in a multi-step (e.g., two-step) RACH. For example, the WTRU may request SI specific to the PSCell via the multi-step RACH. A WTRU may obtain separate DC_Inactive_SI for one or more (e.g., all) potential PSCells for a given PCell, for example, using a single request. The WTRU may obtain SI for a set of SCells associated with the SN (e.g., according to a preconfigured SCell list). For example, the WTRU is configured with the Scell list when the WTRU transitions from a RRC_CONNECTED state to a RRC_INACTIVE state. The WTRU may include (e.g., in the SI request) information indicative of the SCell list that the WTRU is requesting the configuration information from.

A WTRU may receive and/or read a DC_Inactive_SI (e.g., directly) from a SI broadcast of an SN. A WTRU may determine, assume, or be configured to know that information may be broadcast, for example, in a SIB or SI message that may be provided on a cell that may serve as a PSCell (e.g., in a non-standalone (NSA) NR Cell). A WTRU may obtain validity information (e.g., a value tag) and/or scheduling information that is associated with cell reselection SI from a master PCell. A WTRU may determine whether and when to acquire new SI (e.g., associated with SN reselection parameters), for example, based on the acquisition of validity and/or scheduling information in a minimum SI (e.g., that may be broadcast by a PCell). A WTRU may receive validity information and/or scheduling information (e.g., directly) from a SN. A WTRU may read a minimum SI that may be broadcast periodically (e.g., at every wakeup of WTRU's INACTIVE state DRX cycle) by a PSCell, for example, to determine whether to acquire new DC_Inactive_SI.

The WTRU may receive the validity information for the SI of the SCells from the PCell through an SI request procedure and may receive the actual SI associated with SCell from (e.g., directly from) a broadcast of the SCell. The PCell and SCell may not broadcast the scheduling and/or validity information of the SCell's SI, and the SCell may not broadcast the SI (e.g., the actual SI). The WTRU may trigger the SCell to initiate a broadcast of the SCell's related SI (e.g., by sending an SI request to the MN). The WTRU may (e.g., at the same time) receive scheduling and validity information from (e.g., directly from) the PCell.

A WTRU may obtain SI for a PSCell (e.g., the SN cell) from previously obtained SI. The WTRU may store previously obtained SI for a cell (e.g., a SN cell and/or a PSCell). The WTRU may have previously obtained the SI while the WTRU was camped/connected to the cell (e.g., connected to the cell as a PCell). The WTRU may have previously obtained the SI with or without dual connectivity configured. The WTRU may use the previously obtained SI when for the cell (e.g., when the WTUR uses the cell as a SN cell and/or a PSCell).

A WTRU may receive an indication of an SN configuration in a paging message.

A WTRU may receive a notification, which may indicate to the WTRU to use a new SN configuration (e.g., applicable to one or more SN cells (PSCells/SCells)). For example, the WTRU may receive the notification in a paging message. The WTRU may receive the paging message from a MN. The WTRU may receive (e.g., in a paging message), an indication that an SI change is applicable to a DC_Inactive_SI.

A WTRU is configured with a list of potential PSCells/SN SCells.

A WTRU is configured (e.g., implicitly or explicitly) with a list of SCG cells in which the WTRU may, for example, perform mobility while in a RRC_INACTIVE state, direct data/control transmission (e.g., without transitioning to a RRC_CONNECTED state) while in a RRC_INACTIVE state, and/or for which the WTRU may perform one or more measurements that may initiate a transition to a RRC_CONNECTED state, e.g., to update a WTRU's DC context in a network. Such list(s) may be configured at the WTRU while the WTRU is in a RRC_CONNECTED state or configured at the WTRU during the transition from a RRC_CONNECTED state to a RRC_INACTIVE state.

A WTRU may be configured with one or more triggers for the WTRU to transition to and/or from a RRC_CONNECTED state and/or one or more triggers for the WTRU to perform an area update. For example, the triggers may be based on the WTRU's mobility and/or the WTRU's state with respect to a SN.

A WTRU may transition to a RRC_CONNECTED state or perform an area update based on one or more triggers (e.g., mobility events, measurements that may be related to a PSCell or SCell, or traffic characteristics that may be related to a PSCell or SCell). A transition to the RRC_CONNECTED state may be performed (e.g., by a WTRU), for example, to inform a network of one or more of the following: a need to update the PSCell of a DC configuration; a need to clear/update a context in one or more network nodes; and/or a WTRU's movement outside of a specific area of SN coverage. As described herein, a WTRU may transition to the RRC_CONNECTED state based on a trigger (e.g., quality measurements that may be related to a PSCell or SCell, or traffic characteristics that may be related to a PSCell or Scell). The trigger may include comparing a quality measurement or traffic characteristic to a threshold.

A transition to a RRC_CONNECTED state may, for example, follow a procedure that may be a resume procedure (e.g., a resume procedure for NR). An area update procedure may, for example, follow a procedure that may be similar to a RAN area update procedure for NR.

A WTRU may be configured with a trigger for the WTRU to transition to a RRC_CONNECTED state. The configuration of triggers to transition to a RRC_CONNECTED state may be provided, for example, via RRC signaling (e.g., dedicated RRC signaling while in a RRC_CONNECTED state). The RRCH signaling may be received from an MN or from (e.g., directly from) an SN (e.g., via signaling radio bearer <NUM> (SRB3)). A WTRU may (e.g., also) receive a trigger configuration in a message, which may suspend a WTRU to a RRC_INACTIVE state. A WTRU may (e.g., when a configuration is required to be sent by an SN) receive a configuration in an encapsulated RRC message that may be generated by an SN (e.g., in the case of MR-DC).

A WTRU may be configured with a trigger for the WTRU to transition to the RRC_CONNECTED state based on the cell quality of a list of cells.

A WTRU may be configured with a list of cells (e.g., cell IDs) that may correspond to a range of potential PSCell candidates while the WTRU is in a RRC_INACTIVE state. A set of PSCell candidates may, for example, correspond to cells that are associated with a single SN, a single security key for the SN. A set of PSCell candidates may, for example, correspond to a list of cells in which a CN-RAN connection may be maintained during mobility.

A WTRU may be configured with a measurement event that may be associated with a list of cells. A measurement event (e.g., when triggered) may initiate a transition to a RRC_CONNECTED state and may be defined, for example, based on a fact that one or more cells may no longer be suitable for communication. One or more of the following may apply: a measured quality of all or a subset of SCG cells may fall below a threshold, e.g., for a period of time; a measured quality of a PSCell and a given number of other cells in a list may fall below a threshold, e.g., for a period of time; and/or a measured quality of one or more cells that are not part of a list of cells (e.g., a list of PSCells) may become a threshold better than a subset of cells in the list of cells, e.g., for a period of time.

A WTRU may be configured with a trigger for the WTRU to transition to the RRC_CONNECTED state based on cell quality within an area.

A measurement event (e.g., as described herein) may be defined, for example, by the absence of at least one cell broadcasting a signature, a set of related signatures, and/or an identifier that may be specific to an area or list of cells (e.g., an area ID). A WTRU may determine that a signature(s) or an area ID is similar to (e.g., the same as) a signature/area ID that is associated with a PSCell (e.g., when the WTRU was in a RRC_INNACTIVE state). A transition to a RRC_CONNECTED state or an area update procedure may be initiated, for example, based an inability to maintain a certain measurement quality for at least one cell. For example, a transition to a RRC_CONNECTED state or an area update procedure may be initiated based on a measurement quality metric falling below a threshold.

A WTRU may be configured with a trigger for the WTRU to transition to a RRC_CONNECTED state based on inactivity.

A WTRU may be configured, for example, with an inactivity timer or a SCG-ReleaseTimer (e.g., a RRC configured SCG-ReleaseTimer). The inactivity timer may be associated with data transmissions to an SN (e.g., by the WTRU). A WTRU may transition to the RRC_CONNECTED state, for example, upon expiration of the inactivity timer. The inactivity timer may be started, for example, when a WTRU transitions to the RRC_INACTIVE state. The inactivity timer may be reset. for example, when one or more of the following occurs: a WTRU transmits and/or receives data on a DRB and/or SRB that is associated with (e.g., only associated with) an SN (e.g., an SCG DRB), the WTRU transitions to the RRC_CONNECTED state, and/or the WTRU transitions to the RRC_INNACTIVE state (e.g., subsequently transitions back to a RRC_INACTIVE state). The resetting of an inactivity timer for a split DRB (e.g., a DRB where data may be transmitted to an MN or SN) may depend on the UL path selected for transmission of the data. The rules for determining the UL path for a split DRB while a WTRU is in the RRC_INNACTIVE state may be similar to (e.g., the same as) the rules for determining the UL path while the WTRU is in the RRC_CONNECTED state. Also, or alternatively, the rules for UL path determination (e.g., and/or the rules for resetting the inactivity timer) for a split DRB while a WTRU is in the RRC_INNACTIVE state may not be similar (e.g., different) to the rules for UL path determination while the WTRU is in the RRC_CONNECTED state when, for example, the WTRU is configured to transmit data to an MN on certain split bearers while in the RRC_INACTIVE state.

A WTRU may be configured with a trigger to indicate that the WTRU is to transition to the RRC_CONNECTED state based on MN mobility.

A WTRU may be configured with a trigger to indicate that the WTRU is to transition to the RRC_CONNECTED state, for example, based on MN mobility. A transition may be applicable, for example, (e.g., only) when a WTRU is configured with dual connectivity while in a RRC_INACTIVE state. A WTRU configured with DC while in the RRC_INACTIVE state may transition to a RRC_CONNECTED state, for example, when the WTRU performs cell reselection on a cell that is not a PCell (e.g., the current PCell when the WTRU transitions to the RRC_INACTIVE state). Also, or alternatively, a WTRU may be configured with an area (e.g., an area different than a RAN area), which may define a list of PCells (e.g., potential PCells). Reselection of a cell outside of the area may trigger a transition to the RRC_CONNECTED state. A trigger based on MN mobility may be disabled for a WTRU in the RRC_INACTIVE state, for example, when a DC Configuration is not maintained/active.

A WTRU may be configured with a trigger to indicate that the WTRU is to transition to the RRC_CONNECTED state based on a change in configuration (e.g., a change in configuration that no longer allows direct access).

A WTRU may be configured with a trigger to indicate that the WTRU is to transition to the RRC_CONNECTED state when, for example, the SI that is associated with one or more potential PSCells or cells on a SCG changes. When the SI that is associated with one or more potential PSCells or cells on a SCG changes, the WTRU may not access (e.g., may not be able to access) a cell for data transmission without transitioning to the RRC_CONNECTED state. In an example, a WTRU may receive parts of the SI (e.g., the full SI) that may be applicable for an SCG. A WTRU may re-acquire the full SI (e.g., SCG Configuration) while the WTRU is in the RRC_CONNECTED state, for example, to account for a change in an indication (e.g., a specific indication) of the SI. A change in an SI configuration may (e.g., may alternatively) indicate a change in security parameters or data transmission parameters that may (e.g., only) be obtained while in the RRC_CONNECTED state.

A WTRU may be configured with one or more of the triggers described herein. For example, a WTRU may be configured with any of the triggers described herein or any combination of the triggers thereof. A WTRU may transition to the RRC_CONNECTED state or trigger an area update procedure for clearing/updating a context in an NW, for example, upon detecting that a PSCell or any or all cells of an SCG (e.g., configured and/or potential) is not suitable for access (e.g., based on measurements and/or a RRC configured SCG-ReleaseTimer expiration).

A WTRU may behave in one or more of the following ways before, during, and/or after a transition to the RRC_CONNECTED state or an area update.

A WTRU may transition to the RRC_CONNECTED state or may issue an area update based on a trigger, receiving a message, and/or the arrival of UL data. For example, a WTRU may transition the RRC_CONNECTED state or may issue an area update based on one or more of the following: receiving a paging message, the arrival of UL data at the WTRU, and/or one or more triggers. A WTRU may (e.g., as a result of a transition) provide information that may indicate a current mobility state of an SN node.

A WTRU is configured to send information when the WTRU transitions to the RRC_CONNECTED state. For example, a WTRU sends one or more of the following during a transition to RRC_CONNECTED state: an indication to the NW to delete or alter an SN configuration or change a WTRU context to a single connectivity context; an indication to an NW whether a quality of a previously configured PSCell may be above a threshold; an indication of a cell/cells that may have a quality above a (e.g., specific) threshold; an indication of a best cell or a selected cell, for example, from a list of configured potential PSCells (e.g., based on determination mechanisms provided herein); and/or measurements of a set of cells (e.g., including a PSCell, potential PSCells, other detected cells on the same frequency as the PSCell). In an example, inclusion/report of measurements may be based on a triggering of (e.g., specific) events that may occur during mobility while in a WTRU is in a RRC_INACTIVE state (e.g., as described herein).

A WTRU may send the information described herein in one or more messages. For example, a WTRU may send the information described herein in the MSG3 of a RRC procedure and/or in a message following the RRC procedure. The WTRU may perform the RRC procedure for a state transition to the RRC_CONNECTED state or an area update. A WTRU may send an indication of the deletion of an SN configuration in MSG3. A WTRU may send a bitmap of cells (e.g., with reference to a previously configured list of cells) that may have a quality metric above a configured threshold. A WTRU may send a cell ID or other (e.g., similar) identification of a potential cell (e.g., the best potential PSCell). A WTRU may send a null ID, for example, when there is not a potential PSCells that measure above a threshold.

A WTRU may be configured to perform measurement event storage and/or reporting while the WTRU is in the RRC_INACTIVE state.

A WTRU may be configured to perform one or more measurements during a transition to the RRC_CONNECTED state or during an area update. The WTRU may perform the measurements based on the triggering of one or more SN-related events. For example, the SN-related events may be triggered during WTRU mobility while in the RRC_INACTIVE state. A WTRU may include one or more measurements in messaging that is sent to the NW, e.g., during a state transition or an area update for an event (e.g., each event) that is triggered.

A WTRU may be configured with (e.g., certain) events that may trigger a state transition or area update procedure (e.g., immediate state transitions or area update procedures). A WTRU may be configured with one or more events that may trigger inclusion/addition of one or more associated measurements that may be associated with an event in a report (e.g., a final measurement report). A report may be transmitted, for example, when a state transition trigger occurs. Events may result in the addition of one or more measurements on a measurement report without a state transition. A WTRU may (e.g., for such events) cancel or remove previously added measurements, for example, upon a triggering of another event (e.g., when the WTRU leaves and re-enters an area that may be defined by potential PSCells).

A WTRU may convert its RRC context based on SN inactivity.

A WTRU may be configured with an inactivity timer that may be associated with data transmissions to an SN. A (e.g., all) RRC context that is associated with an SN may be updated and/or may be deleted, for example, upon expiration of a timer. A timer (e.g., inactivity timer) may be reset, for example, when a WTRU transmits and/or receives data on a (e.g., any) DRB and/or SRB associated with (e.g., associated only with) an SN (e.g., an SCG DRB). Resetting a timer (e.g., the inactivity timer) for a split DRB (e.g., a DRB where data is transmitted to an MN or SN) may be, for example, conditioned on rules which may be the same as the rules used for determining an UL path for the transmission of data. The rules for resetting a timer (e.g., the inactivity timer) may be, for example, the same as those for RRC_CONNECTED. The rules for resetting a timer (e.g., the inactivity timer) may be different, for example, when a WTRU is in the RRC_INACTIVE state. A WTRU may be configured to transmit data to an MN on a split bearer (e.g., certain split bearers) while in the RRC_INACTIVE state.

A WTRU may (e.g., upon expiration of a timer) convert the WTRU's DC context into a single connectivity context. A WTRU may perform, for example, one or more of the following: delete an SN configuration (e.g., including DC_Inactive_SI); delete a connectivity context (e.g., any connectivity context) that is associated with an SN; stop performing measurements that are related to SN mobility; apply a single connectivity context. A connectivity context may be derived based on, for example, one or more predefined rules and/or a pre-configuration by a network (e.g., when a WTRU transitions to a RRC_INACTIVE state or when a WTRU is with DC).

A WTRU may transmit and/or receive data/control via an SN while in a RRC_INACTIVE state.

A WTRU in a RRC_INACTIVE state may transmit and/or receive data/RRC signaling from a PSCell while remaining in the RRC_INACTIVE state. A WTRU may remain in a RRC_INACTIVE state, for example, with limited operations performed with an MN and while being able to communicate with an SN. For example, when data/RRC signaling is associated with a DRB/SRB that is anchored and transmitted (e.g., only) on an SN leg, a WTRU may remain in a RRC_INACTVIE state (e.g., which may be advantageous).

A WTRU may receive a paging message via a cell (e.g., a MN), for example, to trigger DL data reception from another cell (e.g., a SN).

A WTRU may receive a paging message from a MN, for example, to initiate DL data reception at an SN. The paging message may be received by the WTRU while the WTRU is in a RRC_INNACTIVE state. The WTRU may receive the DL data from the SN (e.g., based on receiving the paging message form the MN) while the WTRU remains in the RRC_INACTIVE state. A paging message may include information that indicates, for example, one or more of the following: a WTRU ID; a cell ID of a PSCell (e.g., to receive the DL data); beam information (e.g., beam ID(s)) of a PSCell (e.g., to receive the DL data); an indication that a WTRU may receive DL data from an SN while remaining in RRC_INACTIVE; a C-RNTI (e.g., to be used by the WTRU for DL data reception); time offset(s) (e.g., to a required access or DL data reception on a PSCell following paging transmission); and/or time duration (e.g., of a data transmission or control channel monitoring via a PSCell). The time duration may be measured, for example, as one or more of the following: an absolute period of time, a number of frames/subframe/slots/minislots, a number of PDUs (e.g., at any given layer) to be transmitted, etc. The paging message may include the uplink timing difference to the PSCell/SCell. The WTRU may use the uplink timing difference to the PSCell/SCell for UL transmissions (e.g., when sending UL data via the SN). The paging message may include an uplink grant in the indicated PSCell/SCell that the WTRU may use for UL transmission to the SN. The paging message may include contention-free random access parameters to be used in the PSCell/SCell (e.g., SN cell) during the random access procedure for the SN cell (e.g., indicated by the network or chosen by the WTRU). Such parameters may be common to the cells (e.g., all the cells) in the configured SCG list, or a list of such parameters corresponding to individual cell(s) in the SCG list may be sent.

A WTRU may receive a paging message from a cell and perform one or more action to enable data and/or control information on another cell. For example, upon successfully receiving a paging message, a WTRU may perform one or more of the following: initiate a RACH procedure or RACH-like procedure to one or more PSCells, for example, to obtain uplink timing alignment and/or beam information for transmission/reception to the PSCell, and/or to inform the NW of a PSCell on which to transmit the DL data; start monitoring a control channel (e.g., using a C-RNTI that may be provided in a paging message or in a RACH procedure to an SN, while remaining in a RRC_INACTIVE state); and/or initiate a resume procedure (e.g., which may include a transition to a RRC_CONNECTED state) with the MN. One or more of the following may apply. The WTRU may initiate a resume procedure with a MN when the SN cell indicated in the paging message is not the best measured cell in the SCG list, or the SN has a quality below a certain threshold. The WTRU may initiate a resume procedure with a MN when the WTRU cannot measure any cells above a threshold (e.g., a quality threshold and/or a measurement result threshold) in the SCG list. The WTRU may initiate a resume procedure with a MN when an initial RACH procedure or RACH-like procedure to an SN cell fails. The WTRU may initiate a resume procedure with a MN when the WTRU does not receive a DL message that includes a C-RNTI on any of the DL SN cells for a specified or configured period of time. The WTRU may initiate a resume procedure with a MN when the WTRU receives UL data (e.g., UL data larger than a certain amount or size, and/or having specific delay or reliability characteristics) while the WTRU is monitoring a DL control channel of the SN cell.

A WTRU may assume, receive, and/or determine a configured, pre-configured, and/or defined time offset. For example, the time offset may be time between when a WTRU receives a paging message on a PCell, and when the WTRU performs a RACH transmission to a PSCell and/or when the WTRU monitors a PSCell control channel.

A WTRU may simultaneously perform the actions described herein to one or more potential PSCells. A WTRU may monitor a control channel on one or more (e.g., all) PSCells in a list (e.g., an SCG list) that may be configured by a network. A WTRU may inform a network of which PSCell to transmit further DL data on. A WTRU may inform a network of which PSCell to transmit further DL data on, for example, following data reception (e.g., only during transmission of a first acknowledgement).

A WTRU may receive a paging message that indicates that the WTRU is to receive DL data from a SN. The WTRU may select a specific cell to use (e.g., select a cell to use from a list of cells) and may indicate the selected cell to the NW. The selected cell(s) may be indicated to the network by initiating a RACH procedure to (e.g., directly to) the cell selected by the WTRU. The WTRU may receive a C-RNTI from the RACH procedure and may monitor the PDCCH using the obtained C-RNTI.

A WTRU may receive a paging message that indicates that the WTRU is to receive DL data from the SN. For example, the paging message may indicate the DL cell on which the WTRU is to receive the data, and/or a C-RNTI and timing offset to be used by the WTRU in the target cell. The WTRU may perform (e.g., directly perform) a RACH to the cell selected by the NW, and/or monitor the PDCCH using the C-RNTI (e.g., C-RNTI provided in the paging message).

A WTRU may transmit data/control to an SN while in a RRC_INACTIVE state.

A WTRU may initiate data transmission, for example, to a last configured PSCell or to a potential PSCell, e.g., upon the arrival of UL data at the WTRU. A WTRU may initiate a data transmission to a PSCell, for example, when data arrives for an SCG bearer. A WTRU may initiate a data transmission to a PSCell, for example, when data arrives for a split bearer that may be anchored in an SN (e.g., when rules configured for transmission to a split bearer require transmission of a packet to the SN). A WTRU may decide to initiate a data transmission (e.g., as opposed to resuming in an SN) based on one or more of the following: when the amount of data to be transmitted on an SCG bearer or split bearer is less than a (e.g., configured) threshold; when data is not pending on (e.g., any) bearers that are non-SCG bearers; when data is associated with a certain priority (e.g., based on data QoS marking, or associated logical channel); and/or when a control (e.g., a RRC message) is associated with a message that may be (e.g., is normally) transmitted on SRB3.

A WTRU may be configured to transmit (e.g., directly to an SN via SRB3) one or more RRC messages that may be associated with SN mobility. A WTRU may perform an area update procedure (e.g., directly to an SN), for example, without a transition to the RRC_CONNECTED state.

A WTRU may perform a security procedure prior to the transmission of data and/or initiating a resume procedure to a SN.

A WTRU may perform data transmission and/or resume procedure with a SN. The WTRU may derive a key for encryption (e.g., a new key for encryption). The WTRU may use the key for the encryption of data/control messages sent to the SN (e.g., prior to such transmission). A WTRU may receive key derivation material for use with the SN. The key derivation material may include a National Communications Commission (NCC) parameter for use with the SN (e.g., SN-NCC) and/or a security key counter (e.g., a new SK-counter). The WTRU may receive the key derivation material during the resume procedure and/or when the WTRU transitions to a RRC_INNACTIVE state (e.g., is suspended to the RRC_INACTIVE state by the MN). The WTRU may receive the key derivation material directly from the SN. The WTRU may receive the SN key derivation material in a container. The container may include a transparent container, which may be received by the WTRU in a suspend message. The suspend message may be provided to the WTRU by a SN. For example, the suspend message may be provided by the SN to the MN (e.g., through inter-node messaging) and the MN ma provide the suspend message to the WTRU as a transparent container within a MN release message. A WTRU may assume that the SN key derivation material to be a function of the MN key derivation material.

As described herein, a WTRU may derive a key for the encryption of data/control sent to a SN based on a function. One or more of the following may be inputs and/or parameters to the key derivation function: a previous key; the cell ID of a PSCell to which the WTUR sends or has sent data or control; the stored WTRU ID; timing information (e.g., SFN, slot number, etc.); a newly derived MN key; and/or information obtained from an MN. As described herein, the WTRU may use a previous key to derive a key for the encryption of data/control sent to a SN. The WTRU may have used the previous key (e.g., a security context previously stored by the WTRU) for data/control sent to a previous SN and/or a previous MN. As described herein, the WTRU may use a newly derived MN key to derive a key for the encryption of data/control sent to a SN. For example, the WTRU may derive the new SN key as a function of the newly derived MN key. As described herein, the WTRU may use information obtained from an MN to derive a key for the encryption of data/control sent to a SN. For example, the WTRU may obtain the information following a RRC message exchange with the MN.

A WTRU may initiate an RRC procedure to the MN to enable derivation of the MN key and/or to obtain keying material for derivation of the SN key. The RRC procedure may be similar to a resume procedure. The RRC procedure may include a resume request message. The resume request message may include an indicator or flag, which may indicate the request to resume to the MN. The WTRU may receive a suspend-like message from the MN in response to the resume request. The message may provide the WTRU with the SN keying material. The message may include information that allows the WTRU to derive the new MN key, and/or keying material (e.g., NCC, sk-counter) applicable to the SN. The WTRU may derive the SN key as a function of the new MN key and/or the received keying material.

A WTRU may directly resume a connection with a SN. The WTRU may be configured in dual connectivity. While in a RRC_INACTIVE state, the WTRU may perform a resume procedure directly to the SN PSCell.

A WTRU may initiation a resume procedure with a SN based on one or more triggers. For example, the WTRU may perform a resume procedure with a SN based on or more of the following triggers.

A WTRU may perform a resume procedure with a SN based on a DRB on which UL data may become available at the WTRU. For example, the WTRU may be configured with an SCG DRB, or an SN terminated DRB. The WTRU may determine to perform a resume procedure to the SN when UL data becomes available for the DRB. The WTRU may perform a resume procedure to the MN (e.g., a PCell) when data arrives for other DRBs. A WTRU may perform a resume procedure to the SN when the WTRU is configured with a split DRB. A WTRU may perform a resume procedure to the SN when data that arrives at the WTRU is for a split DRB.

A WTRU may perform a resume procedure with a SN in response to a paging message. As described herein, the paging message may indicate that DL data is available for the WTRU on an SCG DRB or SN terminated DRB.

A WTRU may perform a resume procedure with a SN based on properties of data that becomes available for transmission. For example, a WTRU may receive data with different QoS requirements (e.g., eMBB vs URLLC), The WTRU may perform a resume directly to the SN directly if the WTRU supports QoS requirements.

A WTRU may perform a resume procedure with a SN based on a barred status on the MN. For example, a WTRU may be rejected during a resume procedure to the MN (e.g., due to NW congestion). In response to the rejected resume procedure to the MN, the WTRU may attempt a resume procedure to a SN.

A WTRU may perform a resume procedure with a SN based on measurements of the PCell/PSCell. A WTRU may perform a resume procedure directly to the SN when a DL cell quality of the SN is above a threshold. Also, or alternatively, a WTRU may perform a resume procedure directly to the SN when the SN quality measurements are better than the MN quality measurements. For example, measurements may be maintained by the WTRU while in a RRC_INACTIVE state.

A WTRU may perform a resume procedure with a SN based on the configuration of a bearer for which UL data has arrived for the WTRU. For example, a WTRU may initiate a resume procedure to the SN when the WTRU receives data for a bearer that can be routed via the SN (e.g., an SCG bearer or a split UL bearer. The WTRU may not initiate a resume procedure to the SN when the WTRU receives data for a bearer that cannot be routed via the SN.

A WTRU may perform a resume procedure with a SN based on keying material. The WTRU may be configured with keying material for the SN when the WTRU was last suspended. The WTRU may initiate a resume procedure to the SN if the WTRU was configured with keying material for the SN when the WTRU was last suspended.

As described herein, a WTRU may perform a resume procedure with a SN. The WTRU may assume the roles of a MN and the SN are changed at initiation of the resume procedure and/or during the resume procedure. The WTRU may determine routing of DRBs/SRBs based on the change of roles. For example, a WTRU may route data from an MCG DRB to the previous SN (e.g., the new MN) following the change of roles. The WTRU may route data from an SCG DBR to the previous MN (e.g., the new SN). The WTRU's bearer reconfiguration may apply to SRBs (e.g., may only apply to SRBs). For example, the SN may take the role of the MN, and the WTRU may reconfigure the DRBs such that the DRBs' path is not changed. The WTRU may reconfigure and/or relocate SRBs. For example, the WTRU may reconfigure SRB1 (e.g., which may have been routed via the previous MN) to be routed to the new MN (e.g., the previous SN). The WTRU may reconfigure SRB1 starting from the resume to the new MN. The WTRU may reconfigure SRB3 to be routed to the old MN (e.g., the new SN).

A WTRU may change the MR-DC configuration. The WTRU may change the MR-DC configuration during a resume procedure to the SN. For example, a WTRU in NG-ENDC (e.g., a MCG in LTE and a SCG in NR) may reconfigure itself to use NE-DC (e.g., MCG in NR and SCG in LTE).

A WTRU may determine the lower layer configuration for a SCG. For example, a WTRU may release the lower layer (PHY, MAC, RLC) configurations of the SCG and may maintain the bearer/PDCP configuration when the WTRU transitions to the RRC_INACTIVE state. Reconfiguration of the lower layers (e.g., signaling overhead associated with transitions to a RRC_CONNECTED state) may not be performed (e.g., skipped). The lower layers of the WTRU may be reconfigured for a specific SCell (e.g., when the WTRU needs to access the Scell).

A WTRU may receive a predefined (e.g., dedicated) configuration for a SCG via signaling. A WTRU may be provided with one or more configurations (e.g., pre-defined dedicated configurations) that may be used in a given SCell (e.g., while the WTRU is in the RRC_INACTIVE state). Such pre-defined dedicated configuration may be associated with a lower-layer configuration, such as configurations of the PHY, MAC, or RLC layers. Such pre-defined dedicated configuration may be associated with a higher layer configuration, such as, PDCP and/or a radio bearer configuration. A configuration (e.g., each predefined configuration) may be associated with an index (e.g., that may be sent in the signaled configuration). The WTRU may receive such pre-defined dedicated configurations via RRC signaling while the WTRU is in a RRC_CONNECTED state, and/or as part of the RRC signaling to transition the WTRU to a RRC_INACTIVE state. Additionally, or alternatively, the WTRU may receive the pre-defined dedicated configurations via RRC signaling on a direct SRB (e.g., a SRB3 configured in the SN). When a WTRU is a RRC_INACTIVE state, the WTRU may receive an index of the dedicated configurations to apply for a given SCell, and/or the WTRU may apply the associated configuration for any operations to a respective SN SCell while the WTRU is in the RRC_INACTIVE state. The WTRU may apply the respective configuration to the SN Scell for, but not limited to, one or more of the following: data transmission while the WTRU remains in the RRC_INACTIVE state, a RACH procedure to SCell, measurements, and/or SI reception.

A WTRU may receive the dedicated configuration to apply for an SCell in SI, which may be broadcast by the SCell. The WTRU may monitor SI in the SCell and may receive an index that may indicate the dedicated configuration be applied for that cell. The WTRU may receive the dedicated configuration to apply for an SCell in a list of index/SCell pairs transmitted in a PCell's SI (e.g., via broadcast and/or provided on-demand). The WTRU may be provided with a configuration (e.g., a single configuration) that the WTRU may apply to a set of SCells (e.g., all SCells in a SCell list).

A WTRU may use a default configuration for SCells. The WTRU may be provided with a default dedicated configuration to be used for one or more SCells (e.g., across all SCells). The default configuration may be preconfigured with specific value(s) in the WTRU or may be provided by RRC signaling or SI in the MN. The default configuration may be applied for (e.g., only for) specific operations while the WTRU is in s RRC_INACTIVE state (e.g., data transmission or RACH procedure to obtain timing alignment) and under (e.g., only under) certain conditions, such as, when the amount of data to be transmitted while in the RRC_INACTIVE state is lower than a threshold, and/or when the type of data to be transmitted has certain characteristics related to latency, reliability, and/or size of transmission. The WTRU may access (e.g., directly access) the SCell while in the RRC_INACTIVE state when the default configuration is applied. If a condition is not met, the WTRU may initiate a procedure to transition to a RRC_CONNECTED state.

The WTRU may obtain a dedicated configuration to resume access to a SCell. The WTRU may utilize a default configuration (e.g., a received default configuration, as described herein) to initiate a procedure to the SCell to obtain a (e.g., a non-default) dedicated configuration to be used in the SCell. The WTRU may perform a RACH procedure, exchange RRC message(s) with an SCell while in the RRC_INACTIVE state, and/or receive (e.g., as part of the signaling) the dedicated configuration to be used for further accesses to that SCell. The WTRU may perform subsequent accesses to the SCell (e.g., for data transmission) with the received non-default (e.g., dedicated) configuration.

The WTRU may invalidate the received non-default configuration as a result of one or more of the following: expiration of a timer, reception of a paging message instructing the WTRU to invalidate the received non-default configuration, reselection to a different cell associated with the MN, a measurement-related event whereby one or more SCells become better/worse than another of the one or more SCells, upon the WTRU's transition to the RRC_CONNECTED state, and/or the network indicates that the WTRU is to invalidate the received non-default configuration, such as, part of the signaling to transition to the RRC_CONNECTED state. The WTRU, upon reception of the dedicated (non-default) configuration, may receive a list of SCells that the configuration may be valid for (e.g., may also be valid for).

<FIG> and <FIG> illustrate examples associated with a WTRU receiving DL data on an SCG cell while remaining in the RRC_INACTIVE state.

<FIG> illustrates an example associated with WTRU mobility. As illustrated in <FIG>, a WTRU may communicate with a network (e.g., the <NUM> CN) via an MCG Bearer and/or a MN. The WTRU may be in communication with the network via an SCG Bearer. The SCG Bearer may be associated with an SN and/or one or more SCG cells (e.g., SCG Cell List1 and/or SCG Cell List2). As illustrated in <FIG>, the WTRU may be configured with an SCG list (e.g., SCG Cell List1). The WTRU may be configured with the SCG list while in the RRC_CONNECTED state, or during a transition from the RRC_CONNECTED state to the RRC_INACTIVE state. The WTRU may be configured with the SCG list via the MCG Bearer and/or the MN. The WTRU may move around (e.g., perform mobility) while in the RRC_INACTIVE state as long as the WTRU remains in the coverage of the cells on the SCG list (e.g., a coverage condition). A coverage condition may be defined such that the WTRU has at least one of the cells on the SCG list being measured (e.g., using a quality metric) as above a threshold (e.g., a configured threshold). When the WTRU moves out of the coverage of the configured list as per the coverage condition (e.g., based on the quality metric for all cells on the SCG list being measured as below the threshold), the WTRU may initiate a transition to the RRC_CONNECTED state. When the WTRU transitions to the RRC_CONNECTED state, the WTRU may be configured with a new SCG list (e.g., SCG Cell List2, as illustrated in <FIG>). After receiving the new SCG list, the WTRU may transition (e.g., immediately transition) to the RRC_INACTIVE state.

<FIG> illustrates an example associated with a WTRU receiving data from a cell while in a RRC_INACTIVE state. As illustrated in <FIG>, a WTRU may communicate with a network (e.g., the <NUM> CN) via an MCG Bearer and/or a MN. The WTRU may be in communication with the network via an SCG Bearer. The SCG Bearer may be associated with an SN and/or one or more SCG cells. Also, or alternatively, the SN may be in communication with the MN. As illustrated in <FIG>, data for the WTRU may arrive at the SCG Bearer and/or the SN. The SN may indicate the arrival of the data to the MN. The indicate of the data's arrival on the SCG may trigger the MN to transmit a paging message. For example, the paging message may be transmitted to the WTRU via the MCG and/or may indicate that data is available for the WTRU on the SCG bearer. The paging message may indicate that the WTRU is to perform RACH on another cell (e.g., a cell on a SCG list). As illustrated in FIG> <NUM>, the WTRU may, e.g., while in the RRC_INACTIVE state, receive the paging message. Upon reception of the paging message, the WTRU may select a cell from an SCG list (e.g., the currently configured SCG list). For example, the WTRU may determine and select the best cell in the SCG list. Upon such determination, the WTRU may perform a RACH procedure to the selected cell and receive data during the RACH procedure (e.g., a MSG4), and/or at another time following the RACH procedure (e.g., by decoding the PDCCH of the selected cell for a period of time).

Systems, methods, and instrumentalities have been disclosed for operating dual connectivity (DC) in an inactive state. System information (SI) may be provided for a DC configuration applicable to an INACTIVE state. A wireless transmit/receive unit (WTRU) may transition to RRC_CONNECTED or perform an area update procedure, for example, based on secondary node (SN)-mobility related triggers, e.g., for a list of potential primary secondary cells (PSCells) in an INACTIVE state DC configuration. Procedures may support measurement events related to a list of potential PSCells. A WTRU may report SN-related measurement information and an indication for context update/deletion, for example, during a state transition or area update. A WTRU may receive paging, which may initiate downlink (DL) data transmission (e.g., directly) from an SN. A WTRU may transmit control/data (e.g., an associated triggering conditions) while in RRC_INACTIVE (e.g., directly) to an SN.

The processes and instrumentalities described herein may apply in any combination, may apply to other wireless technologies, and for other services.

A WTRU may refer to an identity of the physical device, or to the user's identity such as subscription related identities, e.g., MSISDN, SIP URI, etc. WTRU may refer to application-based identities, e.g., user names that may be used per application.

Each of the computing systems described herein may have one or more computer processors having memory that are configured with executable instructions or hardware for accomplishing the functions described herein including determining the parameters described herein and sending and receiving messages between entities (e.g., WTRU and network) to accomplish the described functions.

Claim 1:
A wireless transmit receive unit, WTRU, comprising:
a processor configured to:
receive a configuration information during a procedure for transitioning the WTRU from a connected state to an inactive state, wherein in the inactive state the WTRU is configured to maintain an access stratum, AS, context, and the configuration information indicates a list of cells on which to perform a measurement based on the WTRU being in the inactive state;
perform a measurement on a cell from the list of cells while the WTRU is associated with the inactive state, wherein the cell corresponds to a cell that is supportable by the WTRU as a secondary cell if the WTRU transitioned to the connected state; and
perform a resume procedure, wherein performing the resume procedure comprises transitioning from the inactive state to the connected state, and transmitting a result of the measurement to a base station during the transition from the inactive state to the connected state.