Patent Description:
Systems, methods, and instrumentalities are described herein regarding Radio Resource Control (RRC) state transitions. The state transitions may be performed with a deactivated Secondary Cell Group (SCG).

A wireless transmit/receive unit (WTRU) may be configured for multi-radio dual connectivity (MR-DC). The WTRU may receive configuration information. The configuration information may be associated with a transition to a first activity level (e.g., an RRC CONNECTED state) from a second activity level (e.g., an RRC INACTIVE state). The configuration information may indicate one or more conditions associated with determining whether to resume the first activity level with an SCG activated or deactivated. The one or more conditions may include at least one of a data-characteristic condition, a radio signal level condition, or a WTRU condition. The data-characteristic condition may include at least one of: whether an uplink (UL) data amount threshold is met; or whether a bearer type associated with UL data is a first bearer type or a second bearer type. The WTRU condition may include at least one of: whether a WTRU battery threshold is met; or whether a WTRU overheating level threshold is met.

The WTRU may transition from the first activity level to the second activity level (e.g., based on receiving a suspension command). The WTRU may transition from the second activity level to the first activity level (e.g., based on the arrival of uplink data). The WTRU may select an SCG activation level to use in association with the first activity level based on the one or more conditions in the configuration information, current WTRU conditions, and current network conditions.

The selected SCG activation level may be selected to resume the first activity level with the SCG activated or selected to resume the first activity level with the SCG deactivated. The WTRU may indicate, to a base station, the selected SCG activation level. The WTRU may indicate, to the base station, at least one of: a cause for the selection of the SCG activation level; or a measurement associated with the selection of the SCG activation level. The patent application publication <CIT> shows a WTRU which has a PCell and a SCG that goes into the inactive mode and then wakes up and activates one of the cells in the SCG. The activation is based on paging messages and the actual secondary cell that is selected may be based on measurements.

For example, the communications systems <NUM> may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform (DFT)-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B (eNB), a Home Node B, a Home eNode B, a gNode B (gNB), a NR NodeB, a site controller, an access point (AP), a wireless router, and the like.

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.

11n, <NUM>. 11ac, <NUM>. 11af, and <NUM>. If the primary channel is busy, for example, due to a STA (which supports (e.g., only supports) a <NUM> operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

Reference to a timer herein may refer to determination of a time or determination of a period of time. Reference to a timer expiration herein may refer to determining that the time has occurred or that the period of time has expired. Reference to a timer herein may refer to a time, a time period, tracking the time, tracking the period of time, etc. Reference to a legacy technology or legacy handover, may indicate a legacy technology such as LTE compared to NR, or, a legacy version of a technology, for example an earlier version/release of a technology (e.g., earlier NR release) compared to a later version/release of the technology (e.g., later NR release).

Systems, methods, and instrumentalities are described herein associated with transitions, such as transitions between activity levels, where Radio Resource Control (RRC) state transitions may be used as an illustrative example herein. The state transitions may be performed with a deactivated Secondary Cell Group (SCG).

The WTRU may transition from the first activity level to the second activity level (e.g., based on receiving a suspension command). The WTRU may transition from the second activity level to the first activity level (e.g., based on an arrival of uplink data). The WTRU may select an SCG activation level to use in association with the first activity level based on the one or more conditions in the configuration information, current WTRU conditions, and current network conditions.

The selected SCG activation level may be selected to resume the first activity level with the SCG activated or selected to resume the first activity level with the SCG deactivated. The WTRU may indicate, e.g., to a base station, the selected SCG activation level. The WTRU may indicate, to the base station, at least one of: a cause for the selection of the SCG activation level; or a measurement associated with the selection of the SCG activation level.

A WTRU may be configured to resume from an INACTIVE activity level (e.g., RRC Inactive/RRC INACTIVE state, which may be used as examples herein) to a CONNECTED activity level (e.g., RRC Connected/ RRC CONNECTED state, which may be used as an example herein) with a deactivated or activated SCG.

A WTRU may be configured to save an SCG activation level (e.g., the state of the SCG) when transitioning to a second activity level (e.g., an RRC INACTIVE state). The WTRU may resume (e.g., resume a first activity level, such as RRC CONNECTED state) with the saved SCG activation level (e.g., the saved state of the SCG).

A WTRU may be configured with one or more conditions (e.g., conditions/thresholds) for resuming from the second activity level (e.g., an RRC INACTIVE state) to the first activity level (e.g., an RRC CONNECTED state) with a deactivated SCG or activated SCG. The one or more conditions may include data-characteristic conditions (e.g., load conditions, UL bearer type, UL bearer QoS), radio signal level conditions, or WTRU conditions (e.g., battery level, overheating level, etc.).

A WTRU may determine to resume with a deactivated SCG or activated SCG on transitioning from a second activity level (e.g., an RRC INACTIVE state) to a first activity level (e.g., an RRC CONNECTED state) based on the configured one or more conditions (e.g., conditions/thresholds) and the current state of the WTRU or network. The WTRU may indicate the selected SCG activation level (e.g., SCG state) to the network, e.g., in associated with the resume procedure (e.g., at the start, during the resume, during the completion of the resume procedure, after the completion of the resume procedure).

A WTRU may be configured to take proactive measures or procedures towards the SCG during resumption from the second activity level (e.g., RRC INACTIVE state) to the first activity level (e.g., RRC CONNECTED state) if the WTRU has determined to resume with the SCG activated (e.g., the SCG is activated). The WTRU may perform a random access (RA) procedure (e.g., parallel RA procedure) to the SCG when activating. The WTRU may start sending UL signals (e.g., Channel Quality Indicator (CQI)) for faster activation.

Examples herein may be associated with principles of multi-connectivity. A WTRU may be configured to utilize resources provided by multiple (e.g., two) different nodes, which may be connected via non-ideal backhaul. The nodes may provide access using the same or different radio access technologies (RATs). A first node may act as the master node (MN). The MN may control the resources associated with one or more cells, which may be referred to as Master Cell Group (MCG). A second node may act as the secondary node (SN). The SN may control resources associated with one or more cells, which may be referred to as a Secondary Cell Group (SCG). The MN and SN may be communicatively coupled (e.g., connected) via a network interface. At least the MN may be communicatively coupled (e.g., connected to) the core network.

In examples of dual connectivity, the WTRU may be configured with multiple (e.g., two) medium access control (MAC) entities. One MAC entity may be associated with the MCG, and one MAC entity may be associated with the SCG. The WTRU may be configured to receive and process RRC reconfiguration message(s) via the MCG. The reconfiguration may result in SCG addition, change, modification, or release. The WTRU may be configured to receive and process RRC reconfiguration message(s) via the SCG. The reconfiguration may or may not require coordination with MN.

Examples herein may be associated with the activation and/or the deactivation of SCells, e.g., in NR. NR may support the activation and/or the deactivation of SCells via a medium access control element (MAC CE). If an SCell is deactivated, the WTRU may not perform one or more of (e.g., any) of: transmission of SRS on the SCell; reporting of CSI for the SCell; transmission on UL-SCH; transmission of RACH; monitoring on a physical downlink control channel (PDCCH) on the SCell or for the SCell (e.g., via another activated SCell); or transmission of a physical uplink control channel (PUCCH). A WTRU may be activated/deactivated via a MAC CE activation/deactivation command. A WTRU may (e.g., may also) move from activated to deactivated following the expiration of an SCell deactivation timer.

Examples herein may be associated with dormancy on SCells. Dormancy may provide a more dynamic mechanism for supporting power savings on SCells. For dormancy, the WTRU may maintain some of the functionality of an activated SCell and may save power by not performing PDCCH monitoring. Dormancy may be achieved by switching (e.g., via L1 signaling using DCI) a WTRU to a dormant bandwidth part (BWP). If on the dormant BWP, the WTRU may operate as follows: not transmitting SRS; reporting channel state information (CSI) (e.g., periodic (e.g., only periodic) and semi-static); not monitoring PDCCH on the SCell or for the SCell; performing beam management and beam failure recovery procedure; not transmitting on a PUCCH; and not transmitting on a random access channel (RACH). Dormancy may be associated with an activated SCell state. A WTRU may be changed to a dormant BWP if it is in an SCell active state. A WTRU may or may not be changed to or from a dormant BWP while in an SCell deactivated state. A DCI associated with another SCell may move an SCell from the dormant BWP to a non-dormant BWP.

Examples herein may be associated with SCG dormancy (e.g., SCG/PSCell deactivation). SCG dormancy (e.g., SCG/PSCell deactivation) may include putting the SCG (e.g., the entire PSCell and SCG SCells) in a power saving state if the WTRU does not have the need for the SCG (e.g., if the aggregate data rate of the WTRU bearers are below a certain level, or if the SCG radio quality may not be satisfactory). The SCG may be reactivated from dormancy (e.g., quickly reactivated) if the need arises. This may be accomplished using one or more of the following: adopting the SCell dormancy behavior to the PSCell which may include associating a dormant BWP to the PSCell; having the WTRU effectively operate in single connectivity with the SCG configuration stored and ready to be activated/applied if the need arises; or operating the SCG in a long DRX.

SCG dormancy (e.g., SCG/PSCell deactivation) may include at least one of the following: a single (e.g., only a single) deactivated SCG; no PDCCH monitoring being performed while the SCG is deactivated (e.g., PDCCH monitoring may be reconsidered later); MN configured RRM measurements/reporting (e.g., which may or may not be affected by SCG activation/deactivation) and MN/SN configured measurements on deactivated SCG (e.g., restrictions, relaxations, mobility procedure, etc. may be applied); no SRS transmission on SCG being performed while the SCG is deactivated (e.g., SRS transmission on SCG may be reconsidered later); a RACH for SCG reactivation; a SCG activation level (e.g., activation state, activated state/deactivated state) configured at PSCell addition/change, RRC resume, or HO; and while the SCG is deactivated (e.g., in a deactivated state), the WTRU sends SN configured measurements embedded in an MCG ULInformationTransferMRDC message via SRB1, the WTRU receives an SCG RRCReconfiguration message embedded in an MCG RRC(Connection)Reconfiguration message on SRB1, SCG SCells are not in an active state (e.g., only in a deactivated state, if dormancy is allowed), and SCells are added/reconfigured/released.

Examples herein may be associated with an activity level associated with a WTRU being inactive (e.g., an inactive state, where RRC_INACTIVE state may be used as an example herein). The RRC_INACTIVE state (e.g., second activity level) may be a state where a WTRU remains in CM-CONNECTED and may move within an area configured by NG-RAN (the RAN notification area (RNA)) without notifying NG-RAN. The RRC_INACTIVE state (e.g., the second activity level) may be a compromise between the ACTIVE/CONNECTED state and the IDLE state, where the WTRU may have almost the same power saving benefits of the IDLE state but may be brought back quickly to the connected state if the need arises (e.g., when UL/DL data concerning that WTRU arrives).

If a WTRU is suspended to an RRC INACTIVE state (e.g., the second activity level), it may be allocated an inactive radio network temporary identifier (I-RNTI) by the last serving gNB. The I-RNTI may include a WTRU specific part (e.g., cell radio network temporary identifier (CRNTI) used in the cell if the WTRU was suspended) and a network specific part (e.g., ID of the gNB that was hosting the cell if the WTRU was suspended). The last serving gNB node may keep the WTRU context and the WTRU-associated NG connection with the serving AMF and UPF.

A WTRU in the RRC_INACTIVE state (e.g., the second activity level) may be configured by the last serving gNB with an RNA (RAN notification area), where: the RNA may cover a single or multiple cells, and may be included within the CN registration area; and/or a RAN-based notification area update (RNAU) may be periodically sent by the WTRU and may (e.g., may also) be sent if the cell reselection procedure of the WTRU selects a cell that does not belong to the configured RNA.

The RNA may be configured using a list of cells and/or a list of RAN areas. The list of cells may be provided to a WTRU. The list of cells may include an explicit list of cells (e.g., one or more cells) that constitute the RNA. With respect to the list of RAN areas, the WTRU may be provided with at least one RAN area ID. A RAN area may be a subset of a CN Tracking Area (TA) or equal to a CN TA. A RAN area may be specified by a RAN area ID. The RAN area ID may include a type allocation code (TAC) and optionally a RAN area code. A cell may broadcast one or more RAN area IDs in the system information.

The RNAU may be performed via a resume procedure. In examples, a WTRU may send an RRC Resume Request with a cause value indicating RNAU, and the network may respond with an RRC Release.

If the last serving gNB receives DL data from the UPF or DL WTRU-associated signaling from the AMF while the WTRU is in the RRC_INACTIVE state (e.g., the second activity level), the gNB may page in the cells corresponding to the RNA and may send XnAP RAN paging to neighbor gNB(s) (e.g., if the RNA includes cells of neighbor gNB(s)).

If the WTRU resumes (e.g., in a cell/gNB different from where it was suspended), the WTRU may provide the I-RNTI in the resume request. The target gNB may be able to identify the source gNB from the network specific part of the C-RNTI and may send the context fetch request to the source node.

A WTRU configured with MR-DC may keep an SCG lower layer and bearer configuration when entering the RRC INACTIVE state (e.g., second activity level). If the WTRU resumes (e.g., may be transitioned to the RRC CONNECTED state/first activity level), the network may configure the WTRU to resume with or without the SCG, e.g., in the RRCResume message.

<FIG> illustrates example processing associated with a WTRU triggered transition from an RRC_ INACTIVE state (e.g., second activity level) to an RRC_CONNECTED state (e.g., first activity level).

Referring to <FIG>, the WTRU may resume from an RRC_INACTIVE state (e.g., a second activity level) and may send an RRCResumeRequest to the gNB. The request may provide an I-RNTI that may have been allocated by the last serving gNB. The gNB that received the request from the WTRU may attempt to resolve the identity of the gNB contained in the I-RNTI.

At <NUM>, if the gNB is able to resolve the gNB identity included in the I-RNTI, the gNB may request that the last serving gNB provide WTRU context data. The request may be received at the last serving gNB.

At <NUM>, the last serving gNB may retrieve the WTRU context data and may send the context data to the requesting gNB.

At <NUM>, the gNB that requested and received the context data may communicate the context data to the WTRU. The WTRU may resume an RRC_CONNECTED state (e.g., a first activity level).

At <NUM>, the WTRU may request to complete resumption of the RRC connection (e.g., send a resume complete message). The request may be an RRCResumeComplete message. The WTRU may multiplex user data with the request, e.g., if the UL grant provided by the gNB allows.

At <NUM>, if loss of DL user data buffered in the last serving gNB is prevented, the gNB may provide forwarding addresses.

At <NUM>, the gNB may perform a path switch. The gNB may generate and send a path switch request. The request may be received at an AMF.

At <NUM>, the AMF may send a path switch request response to the gNB.

At <NUM>, the gNB may trigger the release of the WTRU resources at the last serving gNB.

If the WTRU triggered the resume procedure for RAN area update, the network may respond to the RRC Resume request with an RRC Release message and the procedure may end.

<FIG> illustrates example features associated with a triggered (e.g., network triggered) transition from an RRC_INACTIVE state (e.g., second activity level) to an RRC_CONNECTED state (e.g., first activity level).

At <NUM>, a RAN paging trigger event (e.g., incoming DL user plane, DL signaling from 5GC, etc.) may occur.

At <NUM>, RAN paging may be triggered. The paging may be triggered in (e.g., only in) the cells controlled by the last serving gNB. The paging may be triggered (e.g., also be triggered) by means of Xn RAN paging in cells controlled by other gNBs (e.g., configured to the WTRU in the RNA).

At <NUM>, the WTRU may be paged with the I-RNTI.

At <NUM>, if the WTRU has been successfully reached, the WTRU may attempt to resume from the RRC_INACTIVE state (e.g., the second activity level). Thereafter, processing may be the same or similar to a WTRU triggered transition such as one involving sending the RRC Resume Request, etc..

Mobility may be supported with a deactivated SCG. Examples of behavior when transiting to an RRC INACTIVE state (e.g., second activity level) while the SCG is deactivated are provided herein.

Starting with an activated SCG and deactivating the SCG a short time after determining that SCG deactivation is required or desired may lead to unnecessary signaling and power consumption at the WTRU (e.g., if the WTRU experiences frequent state transitions due to the bursty nature of the WTRU traffic, battery level, or overheating which may remain unchanged or become worse during state transition, etc.).

Examples provided herein may be associated with RRC state transition with a deactivated SCG. The examples may be implemented in connection with NR features such as NR dual connectivity carrier aggregation (DCCA).

Several examples are disclosed for enhanced RRC state transitions from an RRC CONNECTED state (e.g., a first activity level) to an RRC INACTIVE state (e.g., a second activity level) and vice versa, which may take SCG deactivation into consideration. The techniques may be applicable to any kind of dual connectivity, e.g., MR-DC, where the MN may be LTE or NR node. The SN may (e.g., may also) employ NR or LTE.

The terms deactivated SCG and dormant SCG may be used interchangeably. The terms signal and message may be used interchangeably. The terms MN and MCG may be used interchangeably. The terms SN and SCG may be used interchangeably. The terms suspended WTRU and a WTRU in an RRC INACTIVE state (e.g., second activity level) may be used interchangeably. The terms SCG activation level and SCG activation state may be used interchangeably.

The WTRU may save/may be instructed to save the SCG's activation level (e.g., the SCG activation state, for example activated or deactivated) when transitioning to the RRC INACTIVE state (e.g., the second activity level) from the RRC CONNECTED state (e.g., the first activity level). The SCG activation level (e.g., the SCG activation state) may include an activated SCG (e.g., the SCG in an activated state) or a deactivated SCG (e.g., the SCG in a deactivated state). The transition to the RRC INACTIVE state (e.g., the second activity level) from the RRC CONNECTED state (e.g., the first activity level) may be based on receiving a suspension command. In examples, the WTRU may rely on default behavior (e.g., the WTRU may store the SCG's state as deactivated in the WTRU inactive AS context or the WTRU may store the SCG's activation level (e.g., the SCG's activation state). In examples, the WTRU may use an indication in the RRC Release message that indicates whether the SCG's activation level (e.g., SCG's activation state) is to be stored in the WTRU inactive AS context.

The SCG being deactivated (e.g., the SCG being in a deactivated state) may be kept by the WTRU if a deactivation was triggered by the WTRU (e.g., due to low battery or low UL data traffic to SCG bearers, etc.), e.g., before the WTRU becomes suspended. The SCG being deactivated (e.g., the SCG being in a deactivated state) may be kept by the WTRU if a deactivation was triggered by the network, e.g., before the WTRU becomes suspended. The SCG being deactivated (e.g., the SCG being in a deactivated state) may be kept by the WTRU based on an indication (or a lack of indication) in the RRC Release message that suspends the WTRU to the RRC INACTIVE state (e.g., the second activity level).

A WTRU may be configured to receive configuration information (e.g., explicit configuration information) from the network to resume the SCG in a given SCG activation level (e.g., SCG activation state) if resuming to the RRC CONNECTED state (e.g., the first activity level) from the RRC INACTIVE state (e.g., the second activity level). The configuration information may indicate one or more conditions associated with determining (e.g., selecting) which SCG activation level (e.g., the SCG activation state) to resume in. The WTRU may receive an indication from the network indicating which SCG activation level (e.g., the SCG activation state), for example activated or deactivated, should be used if the WTRU resumes. The SCG activation level (e.g., the SCG activation state) may include an activated SCG (e.g., the SCG in an activated state) or a deactivated SCG (e.g., the SCG in a deactivated state). The WTRU may receive the indication from the network in the RRC Release message if the WTRU is suspended (e.g., receives a suspension command). The network may indicate to the WTRU to resume with the determined (e.g., selected) SCG activation level (e.g., SCG activation state) if subsequently resuming based on the one or more conditions in the configuration information, current WTRU conditions, and/or current network conditions. The WTRU may obtain this indication in the Random Access Response (RAR) message in response to the RA that the WTRU sent to initiate the resume procedure. The WTRU may obtain this indication in the RRC Resume message if the WTRU is resumed.

The WTRU may receive configuration information from the network for the WTRU to indicate an SCG activation level (e.g., an SCG activation state) implicitly when resuming from the RRC INACTIVE state (e.g., the second activity level) to the first activity level (e.g., RRC_CONNECTED). The SCG activation level (e.g., the SCG activation state) may include an activated SCG (e.g., the SCG in an activated state) or a deactivated SCG (e.g., the SCG in a deactivated state). The WTRU may be configured with two I-RNTIs during suspension (e.g., in RRC Release message), one corresponding to a deactivated SCG and the other corresponding to an activated SCG. The WTRU, depending on its preference or pre-configured conditions (e.g., as may be described in examples herein), may use the I-RNTI corresponding to a SCG activation level (e.g., SCG activation state) during the next resume request, where the SCG activation level indicated by the selected I-RNTI may indicate a selected or preferred SCG activation level.

The WTRU may receive configuration information (e.g., using RRC Release, RRC Reconfiguration message) with a one or more preambles to use for RA when resuming. Some of the preambles may be used for indicating preference for a deactivated SCG. Some of the preambles may be used for indicating preference for an activated SCG. The preambles may be specified explicitly (e.g., preamble x may be used for indicating resume with the SCG deactivated, preamble y may be used for indicating resume with the SCG activated). The preambles may be categorized using some mechanism (e.g., odd preambles may be used for SCG activation while even preambles used for SCG deactivation, preambles below a certain value may be used for SCG deactivation while those above used for SCG activation, etc.). The WTRU, depending on its preference or pre-configured conditions (e.g., as described in examples herein), may use the preamble (or one of the preambles, if more than one preamble may be configured) corresponding to its SCG activation level/preferred SCG activation level (e.g., SCG activation state) in the RA message in the next resume request.

The WTRU may be configured to receive conditional configuration information from the network to resume the SCG in a given SCG activation level (e.g., SCG activation state) if resuming from the RRC INACTIVE state (e.g., the second activity level) to the RRC_CONNECTED state (e.g., first activity level). The WTRU may receive conditional configuration information from the network indicating condition(s) to use to determine which SCG activation level (e.g., SCG activation state) to use if the WTRU resumes. The SCG activation level (e.g., the SCG activation state) may include an activated SCG (e.g., the SCG in an activated state) or a deactivated SCG (e.g., the SCG in a deactivated state).

A condition to resume with the SCG deactivated or activated may depend on the radio conditions (e.g., radio signal level conditions) towards the MN or/and the SN. The condition to resume may be SCG deactivated if: the signal level/quality (e.g., RSRP/RSRQ/RNSI) towards the SN is below a certain threshold; the signal level/quality (e.g., RSRP/RSRQ/RSNI) towards the MN is above a certain threshold; or the signal level/quality (e.g., RSRP/RSRQ/RSNI) towards the MN is stronger than the level/quality towards the SN by a certain threshold. A condition to resume with SCG activated may be if: the signal level/quality (e.g., RSRP/RSRQ/RNSI) towards the SN is above a certain threshold; the signal level/quality (e.g., RSRP/RSRQ/RSNI) towards the MN is below a certain threshold; the signal level/quality (e.g., RSRP/RSRQ/RSNI) towards the MN is lower than the level/quality towards the SN by a certain threshold.

A condition to resume with the SCG deactivated or activated may depend on the cause for resuming. The WTRU may resume with SCG deactivated if: the resume is due to a paging (e.g., arrival of DL data); the resume is due to arrival of UL data that belongs to an MCG bearer (e.g., MN terminated MCG bearer, SN terminated MCG bearer); or the resume is due to arrival of UL data that belongs to a split bearer with MCG as the primary path. The WTRU may resume with SCG activated if: the resume is due to a paging (e.g., arrival of DL data); the resume is due to arrival of UL data that belongs to an SCG bearer (e.g., MN terminated SCG bearer, SN terminated SCG bearer); or the resume is due to arrival of UL data that belongs to a split bearer with SCG as the primary path.

The condition to resume with the SCG deactivated or activated may depend on local condition(s) at the WTRU (e.g., WTRU condition(s)). The WTRU may resume with the SCG deactivated if: the WTRU battery level is below a certain threshold; the WTRU overheating level is above a certain threshold; the WTRU mobility level is above a certain level (e.g., high mobility); or, for UL triggered resume, data-characteristic condition(s) such as if the pending UL data is below a certain threshold or the UL data belongs to a bearer with a given QoS (e.g., non GBR bearer, GBR bearer with a bit rate below a certain threshold). The condition may resume with SCG activated if: the WTRU battery level is above a certain threshold; the WTRU overheating level is below a certain threshold; the WTRU mobility level is below a certain level (e.g., high mobility); or, for UL triggered resume, data-characteristic condition(s) such as if the pending UL data is above a certain threshold, the UL data may belong to a bearer with a given QoS (e.g., GBR bearer with a bit rate above a certain threshold), or the UL data may belong to a bearer that may be configured for duplication.

A network may configure the WTRU to determine the SCG activation level (e.g., SCG activation state) depending on the WTRU battery level, but the threshold (e.g., exact thresholds) may be determined by the WTRU without being configured/indicated by the network.

The WTRU may be configured to indicate a selected or preferred SCG activation level (e.g., SCG activation state) if initiating the resume procedure. If the WTRU initiates the resume procedure from an RRC INACTIVE state (e.g., the second activity level), it may indicate to the network to keep the SCG deactivated. This may be either based on WTRU preference or one of the configurations discussed herein (e.g., depending on radio conditions, data type/level, WTRU conditions such as power/overheating levels, etc.).

The WTRU may indicate that it has determined to resume with a deactivated SCG by including an indicator in the RRC Resume Request message (e.g., a Boolean flag with a value of <NUM>). The WTRU may indicate that it has determined to resume with an activated SCG by including an indicator in the RRC Resume Request message (e.g., a Boolean flag with a value of <NUM>).

The lack of an additional indicator in the RRC Resume Request message about the state of the SCG may indicate that the WTRU has determined to resume with a deactivated SCG. The lack of an additional indicator in the RRC Resume Request message about the state of the SCG may indicate that the WTRU has determined to resume with an activated SCG. The WTRU may indicate that it has determined to resume with a deactivated SCG by including an indicator in the RA message preceding the sending of the RRC Resume Request message.

The WTRU may (e.g., additionally) include the cause for requesting (e.g., selecting) the SCG activation level (e.g., the SCG activation state) to be deactivated/activated (e.g., due to radio conditions, due to bearer type, data volume, battery level, overheating, etc.). The additional information may indicate the cause, and/or may include detailed information (e.g., measurement results if the reason may be radio conditions, battery level if the reason may be battery level, etc.).

The WTRU may indicate a selected or preferred SCG activation level (e.g., the SCG activation state) as part of the resume procedure (e.g., as part of completing the resume procedure). If the WTRU completes the resume procedure from an RRC INACTIVE state (e.g., second activity level), it may indicate to the network to keep the SCG deactivated.

The WTRU may indicate that it has determined to resume with a deactivated SCG by including an indicator in the RRC Resume Complete message (e.g., a Boolean flag with a value of <NUM>). The WTRU may indicate that it has determined to resume with an activated SCG by including an indicator in the RRC Resume Complete message (e.g., a Boolean flag with a value of <NUM>).

The lack of an additional indicator in the RRC Resume Complete message about the state of the SCG may indicate that the WTRU has determined to resume with a deactivated SCG. The lack of an additional indicator in the RRC Resume Complete message about the state of the SCG may indicate that the WTRU has determined to resume with an activated SCG.

The WTRU may indicate information (e.g., additional information) regarding the reason for preference or selection for SCG deactivation or activation. The WTRU, when indicating the SCG activation level (e.g., SCG activation state) via one or more examples described herein, may (e.g., may also) include the reason for requesting the SCG to be deactivated/activated (e.g., due to radio conditions, due to bearer type, data volume, battery level, overheating, etc.).

The WTRU may include information (e.g., additional information) regarding the reason for SCG deactivation/activation preference or selection. If the reason to request SCG deactivation was radio conditions to the MN or SN, the WTRU may include the measurement results towards the MN or/and SN. If the WTRU were to request SCG deactivation due to low battery level, the WTRU may include the current WTRU battery level, etc..

The WTRU may be configured to perform RA (e.g., directly) to the SCG. If the WTRU is configured to select or indicate a preference for the SCG be activated (e.g., based on the examples described herein or WTRU implementation), it may start (e.g., resume) the RA towards the SN in parallel with initiating the resume procedure towards the MN.

The WTRU may be configured to perform resuming (e.g., directly resuming) to the SCG. The WTRU may initiate the resumption towards the SCG, even if it was camping at one of the cells of the MCG, if its selection or preference is the SCG being activated when resuming the RRC CONNECTED state (e.g., the first activity level). In some examples, the WTRU may initiate the resumption towards the SCG, if additional conditions are also fulfilled such as the radio conditions (e.g., radio signal level conditions) towards the SCG being above a certain level. The WTRU, if configured, may use the I-RNTI associated with SCG activation, on resuming (e.g., directly resuming) to the SCG. The WTRU, if configured, may use the RA preamble (or one of the preambles) associated with SCG activation, on resuming (e.g., directly resuming) to the SCG.

The WTRU may be configured with an aspect related to a resume (e.g., a <NUM>-step resume) for RAN area update. If the WTRU initiates the resumption for a RAN area update (e.g., RAN area periodic update timer expiration, re-selection to a cell not belonging to the configured RAN area, etc.), then the WTRU may refrain from performing activities or procedures related to activating the SCG (e.g., RA to the SCG, sending of CQI or other UL reference signals, etc.), e.g., even if, based on one or more examples herein, the WTRU has determined that it may resume with an activated SCG.

A WTRU may be configured to save the SCG activation level (e.g., the SCG activation state) when suspending to the RRC INACTIVE STATE (e.g., the second activity level). The WTRU may be configured with conditions to start (e.g., resume) with the SCG deactivated or activated, and with one or more conditions that indicate that the WTRU select or indicate a preference for an SCG activation level (e.g., the SCG activation state) if resuming (e.g., to a first activity level). A WTRU configured for MR-DC with an MCG and an SCG, and configured with an SCG that may be deactivated, may perform the examples herein.

If transitioning from an RRC CONNECTED state (e.g., first activity level) to RRC INACTIVE state (e.g., second activity level) (e.g., when receiving of RRC Release message), the WTRU may save the SCG activation level (e.g., the SCG activation state). The SCG activation level (e.g., the SCG activation state) may be an activated SCG (e.g., the SCG in an activated state) or a deactivated SCG (e.g., the SCG in a deactivated state). The saving of the SCG activation level (e.g., the SCG activation state) may be dependent on at least one of the following: an indication from the network in the RRC Release message; a pre-configuration before the reception of the RRC release message, either via dedicated or broadcast signaling; or if SCG was deactivated, the reason why SCG was deactivated (e.g., to save the state if deactivation was due to low battery).

<FIG> illustrates an example of selecting an SCG activation level (e.g., an SCG activation state) associated with a transition to a RRC CONNECTED state (e.g., first activity level) from an RRC INACTIVE state (e.g., second activity level), where one or more of the illustrated features may be performed. The WTRU may receive configuration information from the network. The configuration information may be associated with transition to a RRC CONNECTED state (e.g., first activity level) from an RRC INACTIVE state (e.g., second activity level). The configuration information may indicate one or more conditions to determine (e.g., select and/or indicate a preference for) the SCG activation level (e.g., the SCG activation level) state if resuming (e.g., subsequently resuming) to the RRC CONNECTED state (e.g., the first activity level). The SCG activation level (e.g., the SCG activation state) may include an activated SCG (e.g., the SCG in an activated state) or a deactivated SCG (e.g., the SCG in a deactivated state). The one or more conditions to determine the SCG activation level (e.g., SCG activation state) may include whether a saved SCG activation level is SCG activated or SCG deactivated (e.g., resume with activated SCG if the SCG was active when the WTRU was suspended, resume with deactivated SCG if the SCG was deactivated when the WTRU was suspended). The one or more conditions to determine the SCG activation level (e.g., SCG activation state) may include whether a reason for triggering of the resume satisfies a condition. For example, if the resume to the RRC CONNECTED state (e.g., the first activity level) is triggered by arrival of the UL data, the reason for the trigger may include data characteristic conditions such as at least one of: the amount of UL data satisfying a threshold (e.g., resume with SCG deactivated if UL data volume is below a certain threshold); the QoS of the UL data satisfies a condition (e.g., resume with SCG deactivated if UL data belongs to a non GBR bearer); or the bearer type satisfies a condition (e.g., resume with SCG deactivated if UL data belongs to an MCG bearer or a split bearer with MCG as the primary path). The one or more conditions to determine the SCG activation level (e.g., the SCG activation state) may include whether radio conditions towards the MCG or/and SCG satisfy condition(s) (e.g., resume with SCG deactivated if signal quality towards the SCG is below a certain threshold). The one or more conditions to determine the SCG activation level (e.g., the SCG activation state) may include WTRU conditions such as a battery level at the WTRU satisfies a condition(s) (e.g., resume with SCG deactivated if the battery level is below a certain threshold) or the WTRU overheating level satisfies a condition(s) (e.g., resume with SCG deactivate if the WTRU overheating level is above a certain threshold).

If transitioning from an RRC INACTIVE state (e.g., a second activity level) to an RRC CONNECTED state (e.g., a first activity level) (e.g., via arrival of UL data, RAN or CN paging indicating arrival of DL data, etc.), the WTRU may determine (e.g., select and/or indicate a preference for) to resume with an activated SCG or a deactivated SCG (e.g., the SCG in the activated or deactivated state), depending on the configured conditions, current WTRU conditions, and current network conditions. The WTRU may indicate the determination (e.g., the selection and/or indication of the preference for) to the network (e.g., base station), where the indication may be one or more of the following: an indication in the RA procedure at the state of the resume procedure (e.g., using a preconfigured preamble(s) to indicate preference to start (e.g., resume) with the SCG deactivated or activated); an indication in the RRC Resume Request message which may be an explicit indication (e.g., a Boolean flag set to TRUE for deactivated SCG or FALSE for activated SCG, or vice versa) or an implicit indication (e.g., using different I-RNTI values for indicating to be resumed with SCG activated or deactivated); or an indication in the RRC Resume Complete message.

The WTRU (e.g., in addition to the indication) may include the cause for indicating (e.g., selecting and/or indicating the preference for) the deactivated or the activated SCG (e.g., measurement results, BSR, battery level, overheating level, etc.).

If the WTRU determines to start (e.g., resume) with the SCG in activated state, the WTRU may perform one or more of the following: start RA towards the SCG (e.g., in parallel with the RA with the MCG); or start to send faster CQls for the PSCell (and SCG SCells) for faster activation of the SCG.

A WTRU may be configured to resume with a given SCG activation level (e.g., SCG activation state). A WTRU configured for MR-DC with an MCG and an SCG, configured with an SCG that may be deactivated, and currently operating in the RRC INACTIVE state (e.g., second activity level), may receive an indication from the network to resume with the SCG activated or deactivated (e.g., in the SCG activated or deactivated state). The indication may include one or more of the following: an indication in the RRC Release message if the WTRU may be suspended; a pre-configuration before the reception of the RRC Release message, either via dedicated or broadcast signaling; a broadcast indication while the WTRU may be in INACTIVE state; an indication in the RAN or CN paging (e.g., in case activation was due to arrival of DL data) received while the WTRU is in INACTIVE state; an indication in the Random-Access Response (RAR) message during the RA phase of the resume procedure; or an indication in the RRC Resume message.

The indication from the network to resume with the SCG activated or deactivated (e.g., in the SCG activated or deactivated state) may include an explicit indication (e.g., a Boolean flag in the RRC Resume message set to TRUE for deactivated SCG or FALSE for activated SCG, or vice versa) or an implicit indication (e.g., a preconfigured value or range of values in the RAR message that may be associated with a deactivated/activated SCG).

Although features and elements described herein are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without other features and elements.

The description herein may be provided for exemplary purposes and does not limit in any way the applicability of the described systems, methods, and instrumentalities to other wireless technologies and/or to wireless technology using different principles, when applicable. The term network in this disclosure may refer to one or more gNBs which in turn may be associated with one or more Transmission/Reception Points (TRPs) or any other node in the radio access network.

Although the implementations described herein may consider 3GPP specific protocols, it is understood that the implementations described herein are not restricted to this scenario and may be applicable to other wireless systems. For example, although the solutions described herein consider LTE, LTE-A, NR or <NUM> specific protocols, it is understood that the solutions described herein are not restricted to this scenario and are applicable to other wireless systems as well.

Claim 1:
A wireless transmit/receive unit, WTRU, (<NUM>) comprising:
a processor configured to:
receive configuration information, wherein the configuration information is associated with a transition to a first activity level from a second activity level, and wherein the configuration information indicates conditions associated with determining a secondary cell group, SCG, activation level associated with resumption of the first activity level, wherein the SCG activation level is an activated SCG or a deactivated SCG;
transition from the first activity level to the second activity level;
transition from the second activity level to the first activity level;
determine the SCG activation level based on an evaluation of the conditions in the configuration information, wherein the conditions in the configuration information comprise a WTRU condition and a network condition, wherein the network condition comprises at least whether a bearer type associated with UL data is a first bearer type or a second bearer type; and
indicate, to a base station, the determined SCG activation level.