Patent Description:
The present disclosure relates to connection resume in a cellular communications system.

There may be different ways to deploy a Fifth Generation (<NUM>) network with or without interworking with Long Term Evolution (LTE), which is also referred to as Evolved Universal Terrestrial Radio Access (E-UTRA), and Evolved Packet Core (EPC), as depicted in <FIG>. The illustrated options are:.

In principle, NR and LTE can be deployed without any interworking, denoted by NR Stand-Alone (SA) operation. Accordingly, an NR RAN node (referred to as an NR base station (gNB) in NR) can be connected to a 5GCN and an enhanced or evolved Node B (eNB) in LTE can be connected to an EPC with no interconnection between the two (Option <NUM> and Option <NUM> in <FIG>). On the other hand, the first supported version of NR is the so-called EN-DC, illustrated by Option <NUM> of <FIG>. In such a deployment, DC between NR and LTE is implemented with LTE functioning as the master node and NR functioning as the secondary node. The RAN node (gNB) supporting NR may not have a control plane connection to the core network (EPC); instead, it relies on the LTE RAN node (eNB) as master node (referred to as a Master eNB (MeNB)). This is also referred to as "Non-SA NR. " Notice that in this case the functionality of an NR cell is limited and would be used for connected mode User Equipments (UEs) as a booster and/or diversity leg, but an RRC_IDLE UE cannot camp on these NR cells.

With the introduction of 5GCN, other options may be also valid. As mentioned above, Option <NUM> supports SA NR deployment where the gNB is connected to the 5GCN. Similarly, LTE can also be connected to the 5GCN using Option <NUM> (also known as eLTE, E-UTRA/5GCN, or LTE/5GCN and the node can be referred to as a next generation eNB (ng-eNB)). In these cases, both NR and LTE are seen as part of the Next Generation RAN (NG-RAN) (and both the ng-eNB and the gNB can be referred to as NG-RAN nodes). It is worth noting that Option <NUM> and Option <NUM> of <FIG> are other variants of DC between LTE and NR which will be standardized as part of NG-RAN connected to 5GCN, denoted by Multi-Radio DC (MR-DC). Options <NUM> and <NUM> of <FIG>, where the gNB is connected to the EPC (with and without interconnectivity to LTE), are also possible, although they seem to be less practical and hence they will not be pursued further in 3GPP.

As migration for these options may differ from different operators, it is possible to have deployments with multiple options in parallel in the same network. For example, an eNB base station may be configured to support Options <NUM>, <NUM>, and <NUM>, while a gNB may be configured to support Options <NUM> and <NUM>.

The User Plane (UP) and Control Plane (CP) protocol stacks in NR are shown in <FIG>, respectively. When reconfiguring a UE, the NR network transmits an RRCReconfiguration message containing a RadioBearerConfig and a CellGroupConfig Information Element (IE). The RadioBearerConfig configures the Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP) protocol layers for all Data Radio Bearers (DRBs) and the PDCP protocol layer for all Signaling Radio Bearers (SRBs). The CellGroupConfig configures the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers for all Radio Bearers (RBs).

In the case of NR-DC, the RRCReconfiguration message may contain one or more RadioBearerConfig messages (e.g., radioBearerConfig and radioBearerConfig2) and one or more CellGroupConfig messages (e.g., masterCellGroup and secondaryCellGroup). Each RadioBearerConfig may contain a list of DRBs and/or SRBs, which are terminated in the respective node, as well as a configuration for the security algorithms to be used.

The CellGroupConfig on the other hand may contain configurations for one or more cells associated to a respective Master Node (MN) or a respective Secondary Node (SN). One of the cells may be denoted as a Special Cell (SpCell), (Primary Cell (PCell) or Primary Secondary Cell Group (SCG) Cell (PSCell)), which will be the primary cell used for communication. The other cells will be Secondary Cells (SCells) which are monitored in case any of them can provide better radio conditions than the SpCell. The CellGroupConfig may also contain a list of RLC bearers which are associated to a specific RB with the parameter servedRadioBearer.

As can be seen in <FIG>, DRBs can be terminated in either the MN or the SN and be transmitted via either the Master Cell Group (MCG) (MCG bearer), SCG (SCG bearer), or both (split bearer). Any combination of MN and SN terminated bearers as well as MCG, SCG, and split bearers can be configured for a UE. For SRBs, SRB1 and SRB2 are terminated in the MN and can be either MCG or split bearers, whereas SRB3 is terminated in the SN and can only be an SCG bearer. Although the concept shown here shows the system connected to a 5GCN, the same principles applies to an EN-DC connected to an EPC.

When the UE is configured with two RadioBearerConfigs and two CellGroupConfigs, each RLC bearer in either CellGroupConfig can be associated to a RB terminating in either the MN or the SN. In case of split bearers, an RLC bearer in masterCellGroup and an RLC bearer in secondaryCellGroup are configured with the same RB identity in the servedRadioBearer.

In combination with DC solutions between LTE and NR, it is also possible to support Carrier Aggregation (CA) in each cell group (i.e., MCG and SCG). In that case, one or more of the SCells in the CellGroupConfig is also used to provide more radio resources to the UE. Initially, it was only DRBs which could be used in CA, but, in Release <NUM>, PDCP duplication was introduced where the same data could be transmitted via two RLC bearers for both DRBs and SRBs to provide redundancies and increased reliability.

<FIG> illustrates UE state machine and state transition between NR/5GCN, E-UTRA/EPC, and E-UTRA/5GCN. As can be seen in <FIG>, it may be possible to move an ongoing UE connection (e.g., UE is in RRC_CONNECTED state) between two Radio Access Technologies (RATs) (e.g., NR/5GCN, E-UTRA/EPC, or E-UTRA/5GCN) using a handover procedure. Additionally, (not shown) it is possible for the network to move the UE to the other RAT by sending a Release message with re-direct information. When the UE is in IDLE or INACTIVE state, the cell reselection procedure will be used when transitioning between the RATs.

In NR and E-UTRA (i.e., LTE connected to 5GCN), there may exist a new RRC state called RRC_INACTIVE. Hereinafter, an NG-RAN refers to a RAN in which either an NR or an LTE RAN is connected to a 5GCN.

In RRC_INACTIVE, the UE stores certain configurations (e.g., DRB configurations and physical layer parameters). When the UE needs to resume the connection, it transmits an RRCConnectionResumeRequest and RRCResumeRequest in LTE and NR, respectively. The UE can then reuse the stored settings to help reduce the time and signaling needed to enter RRC_CONNECTED. In addition, in E-UTRA EPC, a suspended Radio Resource Control (RRC) connection state has been introduced. In this regard, when the UE enters RRC_IDLE from RRC_CONNECTED, it stores the configurations that can later be resumed.

In Release <NUM> (first release) of the NG-RAN standard, it has been agreed to not support direct transition between RRC_INACTIVE in LTE/E-UTRA and RRC_INACTIVE in NR. Hence, a Release <NUM> UE in RRC_INACTIVE in one RAT performing cell reselection to the other RAT would trigger the UE to release its Access Stratum (AS) context, enter RRC_IDLE, and perform a Registration Area Update. In addition, it has been agreed in Release <NUM> that if a UE is configured with MR-DC when entering RRC_INACTIVE, the UE will release the secondaryCellGroup configurations. In addition, if the UE is connected to E-UTRA/EPC or E-UTRA/5GCN either in single connectivity or in (NG)EN-DC when it is suspended to RRC_IDLE with suspended RRC Connection or RRC_INACTIVE respectively, when the UE initiates the RRC resume procedure it will also release the MCG SCell(s).

Note that, in NR, an equivalent message exists for the case of long Inactive Radio Network Temporary Identifier (I-RNTI) of <NUM> bits used as UE identifier RRCResumeRequest1 associated to a different logical channel compared to the short I-RNTI used in the RRCResumeRequest message.

In LTE/NR Release <NUM>, a new Work Item (WI) for enhanced CA/DC operations is being standardized, and in the <NPL>), it has been agreed that:.

These agreements mean that the SCG can be restored, released, or reconfigured during the resumption of an RRC connection. Specifically;.

In LTE, whenever the UE performs a handover, it receives an RRCConnectionReconfiguration message that includes the mobilityControlInfo (see, e.g., Third Generation Partnership Project (3GPP) Technical Specification (TS) <NUM> V15. This contains all the configurations the UE requires to access the target cell and will trigger the UE to perform a random access to it, e.g., in order to obtain synchronization with the cell. Particularly, 3GPP TS <NUM> V15. <NUM> states:
<IMG>.

In case of a handover, the MAC, upon getting the RRCConnectionReconfigurationComplete message and noticing that it is the first time that it is sending data on this link, will initiate the random access procedure.

In case of LTE DC, the secondary radio configuration can contain a field called mobilityControlInfoSCG during SCG change or addition that has a similar functionality as the mobilityControlInfo field in the RRCConnectionReconfiguraiton, but for the SCG. As the UE does not transmit an RRCConnectionReconfigurationComplete directly to the SCG, as this message is only sent to the MCG, the procedures explicitly trigger a random access procedure for the SCG when the UE receives the mobilityControlInfoSCG.

Section <NUM>. <NUM> of 3GPP TS <NUM> V15. <NUM> states:
<IMG>.

In the case of NR, the cell group configuration, which can be either for the MCG or SCG, can contain the reconfigurationWithSync field that provides a similar functionality to the mobilityControlInfo and mobilityControlInfoSCG in LTE (3GPP TS <NUM> V15. Section <NUM>. <NUM> of 3GPP TS <NUM> V15. <NUM> states:
<IMG>.

Document "<NPL>) discloses a system wherein for NR, allows the reconfigurationWithSync field to be included in the RRCResume message and for LTE, allows mobilityControlInfo field to be included in the RRCConnectionResume message.

There currently exist certain challenge(s). As mentioned above, it has been agreed to enable restoring, releasing, or reconfiguring a stored SCG configuration during connection resumption. However, there are several issues related to restoring, releasing, or reconfiguring a stored SCG configuration during connection resumption that need to be addressed.

Systems and methods are disclosed herein for resuming a connection of a wireless communication device suspension to a dormant state while the wireless communication device was operating in Dual Connectivity (DC) with a Master Cell Group (MCG) with a first network node and a Secondary Cell Group (SCG) with a second network node. In one embodiment, a method performed by the wireless communication device comprises receiving a connection resume message with an indication to restore the SCG of the wireless communication device, where the connection resume message comprises information that is mandatory when the connection resume message comprises an indication to restore the SCG. The information that is mandatory comprises information that triggers synchronization and random access towards a Primary SCG Cell (PSCell) (e.g., reconfigurationWithSync or mobilityControlInfoSCG). The method further comprises restoring the SCG in accordance with the connection resume message. In this manner, the wireless device is able to properly restore the SCG because the resume message comprises the information used to trigger synchronization and random access towards the PSCell.

In one embodiment, the SCG is a New Radio (NR) SCG, and the information that is mandatory comprises reconfigurationWithSync. Further, in one embodiment, the MCG is either an NR MCG or an Evolved Universal Terrestrial Radio Access (E-UTRA) MCG.

In one embodiment, the SCG is an E-UTRA SCG, and the information that is mandatory comprises mobilityControlInfoSCG. Further, in one embodiment, the MCG is an NR MCG.

In one embodiment, the information that is mandatory comprises reconfigurationWithSync or mobilityControlInfoSCG, regardless of whether a stored SCG configuration is to be restored without reconfiguration.

In one embodiment, restoring the SCG comprises restoring a stored SCG configuration and initiating random access with a Primary SCG Cell (PSCell) of the restored SCG configuration.

In one embodiment, the connection resume message comprises a delta SCG configuration, and restoring the SCG comprises restoring a stored SCG configuration, applying the delta SCG configuration on top of the restored SCG configuration to provide an updated SCG configuration, and initiating random access with a PSCell of the updated SCG configuration.

In one embodiment, the connection resume message comprises a new SCG configuration, and restoring the SCG comprises applying the new SCG configuration and initiating random access with a PSCell of the new SCG configuration.

Corresponding embodiments of a wireless communication device are also disclosed. In one embodiment, a wireless communication device for resuming a connection after being suspended to a dormant state while the wireless communication device was operating in DC with an MCG with a first network node and an SCG with a second network node is adapted to receive a connection resume message with an indication to restore the SCG of the wireless communication device, where the connection resume message comprises information that is mandatory when the connection resume message comprises an indication to restore the SCG. The information that is mandatory comprises information that triggers synchronization and random access towards a PSCell (e.g., reconfigurationWithSync or mobilityControlInfoSCG). The wireless communication device is further adapted to restore the SCG in accordance with the connection resume message.

Embodiments of a method performed by a network node are also disclosed. In one embodiment, a method performed by a network node for resuming a connection of a wireless communication device after the wireless communication device was suspended to a dormant state while the wireless communication device was operating in DC with an MCG with a first network node and an SCG with a second network node comprises sending, to the wireless communication device, a connection resume message with an indication to restore the SCG of the wireless communication device. The connection resume message comprises information that is mandatory when the connection resume message comprises an indication to restore the SCG, where the information that is mandatory comprises information that triggers synchronization and random access towards a PSCell (e.g., reconfigurationWithSync or mobilityControlInfoSCG).

In one embodiment, the SCG is an NR SCG, and the information that is mandatory comprises reconfigurationWithSync. Further, in one embodiment, the MCG is either an NR MCG or an E-UTRA MCG.

In one embodiment, the network node is the first network node. In another embodiment, the network node is the second network node.

Corresponding embodiments of a network node are also disclosed. In one embodiment, a network node for resuming a connection of a wireless communication device after the wireless communication device was suspended to a dormant state while the wireless communication device was operating in DC with an MCG with a first network node and an SCG with a second network node is adapted to send, to the wireless communication device, a connection resume message with an indication to restore the SCG of the wireless communication device. The connection resume message comprises information that is mandatory when the connection resume message comprises an indication to restore the SCG, where the information that is mandatory comprises information that triggers synchronization and random access towards a PSCell (e.g., reconfigurationWithSync or mobilityControlInfoSCG).

The subject-matter of <FIG> and their descriptions, even if described or named as "embodiment(s)", "invention(s)", "aspect(s)", "example(s)" or "disclosure(s)" etc., does not fully and thus only partly correspond to the invention as defined in the claims, since one or more features present in and required by the independent claims are missing in the "embodiment(s)", "invention(s)", "aspect(s)", "example(s)" or "disclosure(s)" etc. The subject-matter of <FIG> and their descriptions is therefore not covered by the claims and is useful to highlight specific aspects of the claims.

Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

Although the description herein refers to dual connectivity between Evolved Universal Terrestrial Radio Access (E-UTRA) and NR (E-UTRA NR Dual Connectivity (DC) (EN-DC), Next Generation RAN E-UTRA NR DC (NGEN-DC), NR E-UTRA DC (NE-DC)) or between two NR nodes (NR-DC), the solutions would be equally applicable in LTE DC (i.e., two E-UTRA nodes connected to an Evolved Packet Core (EPC) as specified in E-UTRA Release <NUM>) or between two E-UTRA nodes connected to a <NUM> Core Network (5GCN) (currently not supported). Furthermore, if later releases support the UE to connect to more than two nodes, the same solutions would apply to resuming these additional connections.

There currently exist certain challenge(s). As mentioned above, it has been agreed to enable restoring, releasing, or reconfiguring a stored Secondary Cell Group (SCG) configuration during connection resumption. If the SCG is to be restored with no changes to the configurations, then there is no need to include the SCG configuration in the RRCResume message and a restore-SCG flag is sufficient to indicate to the UE that it has to restore the stored SCG configuration before the connection was suspended. This is discussed in previously filed <CIT> and is also described in detail in draft Change Requests (CRs) R2-<NUM>, R2-<NUM>.

As described above, the synchronization to the Primary SCG Cell (PSCell) and the initiation of the random access is triggered by either the inclusion of the mobilityControlInfoSCG if the SCG is LTE (in case of LTE-DC or NE-DC) or including the reconfigurationWithSync in the SCG cell group configuration if the SCG is NR (in case of EN-DC, NGEN-DC, and NR-DC).

If the SCG is to be restored during connection resumption, there is no need to include the SCG configuration. As such, the UE will not receive any mobilityControlInfoSCG or reconfigurationWithSync associated with the SCG. Thus, the UE will not be able to perform synchronization and the required random access towards the PSCell, which is required before the UE can start sending/receiving data to/from the SCG.

Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.

Embodiments of method performed by a wireless communication device (e.g., a wireless terminal or UE) and corresponding embodiments of the wireless communication device are disclosed. In some embodiments, a method performed by a wireless communication device that is resuming a connection after being suspended to a dormant state (e.g., RRC_IDLE with suspended or RRC_INACTIVE) while it was operating in DC with a Master Cell Group (MCG) with a first node (the Master Node (MN)) and a SCG with a second node (the Secondary Node (SN)) is provided. In some embodiments, the method comprises:.

Note that, as understood by those of skill in the art, a "delta SCG configuration" or a "delta configuration of the SCG" is a configuration that includes only changes to the SCG configuration relative to a prior configuration of the SCG.

Embodiments of a method performed by a second network node (LTE eNB or NR gNB) and corresponding embodiments of the second network node are also disclosed. In some embodiments, the method performed by the second network node comprises:.

Embodiments of a method performed by a second network node (LTE eNB or NR gNB) that was operating node as an SN for a wireless communication device (e.g., a UE) that was operating in DC with an MCG with a first node (the MN) and an SCG with the second node before it was suspended and corresponding embodiments of the second network node are also disclosed. In some embodiments, the method comprises:.

Note that, in the wireless communication device embodiments above, it has been assumed that the wireless communication device may receive a delta or full SCG configuration that does not include a mobilityControlInfoSCG or reconfigurationWithSync, and the reception of the resume message with the SCG configuration was used as an implicit indication for the wireless communication device to trigger the synchronization and random access procedure with the SN. However, an alternate solution is to ensure that the SN always includes the mobilityControlInfoSCG or the reconfigurationWithSync whenever it provides a delta or new SCG configuration as a response to the message from the MN to resume the SCG. The first option is what is bolded in the wireless communication device embodiments above, while the second option is what is bolded in the SN embodiments above.

Certain embodiments may provide one or more of the following technical advantage(s). Without this present disclosure, it will not be possible to properly resume the stored SCG because the UE will not get an indication (i.e., a mobilityControlInfoSCG if the SCG was E-UTRA or a reconfigurationWithSync if the SCG was NR) to trigger the synchronization and the random access procedure towards the PSCell.

<FIG> illustrates one example of a cellular communications system <NUM> in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system <NUM> is a <NUM> System (5GS) including an NR RAN or a system that includes a mixture of LTE and NR RAN nodes. In this example, the RAN includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in in LTE are referred to as eNBs and in <NUM> NR are referred to as gNBs or next generation eNBs (ng-eNBs) in the case of LTE RAN nodes connected to the 5GCN, controlling corresponding (macro) cells <NUM>-<NUM> and <NUM>-<NUM>. The base stations <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as base stations <NUM> and individually as base station <NUM>. Likewise, the (macro) cells <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as (macro) cells <NUM> and individually as (macro) cell <NUM>. The RAN may also include a number of low power nodes <NUM>-<NUM> through <NUM>-<NUM> controlling corresponding small cells <NUM>-<NUM> through <NUM>-<NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells <NUM>-<NUM> through <NUM>-<NUM> may alternatively be provided by the base stations <NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as low power nodes <NUM> and individually as low power node <NUM>. Likewise, the small cells <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as small cells <NUM> and individually as small cell <NUM>. The cellular communications system <NUM> also includes a core network <NUM>. The base stations <NUM> (and optionally the low power nodes <NUM>) are connected to the core network <NUM>.

<FIG> is a flow chart that illustrates a method performed by a wireless communication device <NUM> (e.g., a wireless terminal or UE) in accordance with some embodiments of the present disclosure. Optional steps are represented by dashed lines/boxes. In this embodiment, the wireless communication device <NUM> is resuming a connection after being suspended to a dormant state (e.g., RRC_IDLE with suspended or RRC_INACTIVE) while it was operating in DC with a MCG with a first node (the MN) and a SCG with a second node (the SN). As illustrated, the method includes the following steps.

<FIG> is a flow chart that illustrates a method performed by a second network node (e.g., a base station <NUM> or other RAN node (e.g., a LTE eNB or NR gNB) that serves as the SN of an SCG of a wireless communication device <NUM> (e.g., a wireless terminal or UE)) in accordance with some embodiments of the present disclosure. Optional steps are represented by dashed lines/boxes. In this embodiment, the method performed by the second network node comprises:.

<FIG> is a flow chart that illustrates a method performed by a second network node (e.g., a base station <NUM> or other RAN node (e.g., an LTE eNB or NR gNB) that serves as the SN for a wireless communication device <NUM> (e.g., a UE) that was operating in DC with an MCG with a first node (the MN) and an SCG with the second network node before it was suspended in accordance with some embodiments of the present disclosure. In this embodiment, the method performed by the second network node comprises:.

Note that, in the wireless communication device embodiments above, it has been assumed that the wireless communication device may receive a delta or full SCG configuration that doesn't include a mobilityControlInfoSCG or reconfigurationWithSync, and the reception of the resume message with the SCG configuration was used as an implicit indication for the wireless communication device to trigger the synchronization and random access procedure with the SN. However, an alternate solution is to ensure that the SN always includes the mobilityControlInfoSCG or the reconfigurationWithSync whenever it provides a delta or new SCG configuration as a response to the message from the MN to resume the SCG. The first option is what is bolded in the wireless communication device embodiments above, while the second option is what is bolded in the SN embodiments above.

In the following, example realizations of embodiments of the present disclosure during resuming a UE that was operating in EN-DC or NGEN-DC (3GPP Technical Specification (TS) <NUM>) are provided. Text marked in bold font are changes required to enable MCG SCell/SCG resumption that is currently being captured in 3GPP (i.e., exact phrasing not agreed yet). Text marked in bold font and underlined are required changes that are specific to this embodiment of the solution described herein (i.e., synchronization and random access towards the SCG). The example realizations are shown as example specification text that could be included into 3GPP TS <NUM>.

In the following, example realizations of the embodiments of the present disclosure during resuming a UE that was operating in NR-DC or NE-DC (3GPP TS <NUM>) are provided. Text marked in bold font are changes required to enable MCG SCell/SCG resumption that is currently being captured in 3GPP (i.e., exact phrasing not agreed yet). Text marked in bold font and underlined are changes that are specific to this embodiment of the solution described herein (i.e., synchronization and random access towards the SCG). The example realizations are shown as example specification text that could be included into 3GPP TS <NUM>.

Embodiments discussed herein include methods to handle the UE synchronizing with the SCG and initiating random access even if the mobilityControlInfoSCG or the reconfigurationWithSync, which are normally used to trigger these actions, are not present, which is the case if the UE is instructed to restore the SCG without any delta or full configuration of the SCG.

If the UE is provided with an SCG configuration and the mobilityControlInfoSCG or the reconfigurationWithSync are not included, the problem still remains. Here, new conditions to be included in the specifications regarding these fields are proposed so that it can be ensured that a UE will always receive the mobilityControllnfoSCGor reconfigurationWithSync if it receives an SCG configuration with the resume message.

For NE-DC (NR MN, E-UTRA SN), the NR RRCReconfiguration message will contain the E-UTRA RRCConnectionReconfiguration message comprising the SCG configurations. The NR RRCReconfiguration message will contain the field mrdc-SecondaryCellGroupConfig. This in turn will contain the field mrdc-SecondaryCellGroup with the choice set to eutra-SCG. This field will contain an E-UTRA RRCConnectionReconfiguration message. This RRCConnectionReconfiguration message will contain the Information Element (IE) SCG-Configuration, which in turn will contain the field SCG-ConfigPartSCG. This field will in turn contain the field mobilityControlInfoSCG. In some embodiments, the required change proposed herein is to make this field mandatory in case of NE-DC resume when NR RRCResume message includes the E-UTRA RRCConnectionReconfiguration message for the SCG. The NR and E-UTRA messages are shown below with the relevant parts highlighted in in bold font. The required changes are highlighted in in bold font and underlined.

For (NG)EN-DC (MN E-UTRA, SN NR), for (NG)EN-DC, the UE was connected to E-UTRA as MN (either connected to EPC or 5GCN) and NR as SN before being suspended. When the UE resumes, it will receive an E-UTRA RRC message RRCConnectionResume, which can contain the NR SCG configurations in the field nr-SecondaryCellGroupConfig in an embedded NR Radio Resource Control (RRC) message RRCReconfiguration. This NR RRC message RRCReconfiguration will contain the field secondaryCellgroup (with the IE CellGroupConfig) which will contain the field spCellConfig. If the spCellConfig contains the field reconfigurationWithSync, the UE will perform a random access. In the current specification, this field is optional to include.

For NR-DC (MN NR, SN NR), if both the MN and the SN are NR, when the UE resumes from RRC_INACTIVE it will receive an NR RRCResume message which can contain the field mrdc-SecondaryCellGroupConfig containing the mrdc-SecondaryCellGroup set to nr-SCG. This NR RRC message RRCReconfiguration will contain the field secondaryCellgroup (with the IE CellGroupConfig) which will contain the field spCellConfig. If the spCellConfig contains the field reconfigurationWithSync, the UE will perform a random access. In current specification, this field is optional to include. The changes required for the SCG will be the same as for (NG)EN-DC, as the NR SCG configuration will be the same (i.e., make the reconfigurationWithSync field mandatory in case of PSCell resume when RRC reconfigurations are included).

Another embodiment of the present disclosure is to make the reconfigurationWithSync (for NR SCG) or mobilityControlInfoSCG (for E-UTRA SCG) mandatory to include whenever the SCG should be resumed, regardless of whether the old configurations would be restored without reconfigurations. This would mean that the network would have to include the SCG configuration including this field, even if all other configurations are provided with delta configurations. A flow chart that illustrates the operation of a wireless communication device <NUM> in accordance with an example of this embodiment is illustrated in <FIG>.

More specifically, <FIG> is a flow chart that illustrates the operation of a wireless communication device <NUM> for resuming a connection after being suspended to a dormant state while the wireless communication device <NUM> was operating in DC with a MCG with a first network node and an SCG with a second network node. Optional steps are represented by dashed lines/boxes. As illustrated, the wireless communication device <NUM> receives a connection resume message (e.g., an RRC Connection Resume message or RRC Resume message) with an indication to restore the SCG of the wireless communication device <NUM> (step <NUM>). As described above, in this embodiment, the connection resume message comprises information that is mandatory when the connection resume message comprises an indication to restore the SCG where the information that is mandatory comprises information that triggers random access towards a PSCell. For an NR SCG, the information that triggers random access towards the PSCell is reconfigurationWithSync. For an E-UTRA SCG, the information that triggers random access towards the PSCell is mobilityControlInfoSCG. In one embodiment, the information that is mandatory comprises reconfigurationWithSync or mobilityControlInfoSCG, regardless of whether a stored SCG configuration is to be restored without reconfiguration, as described above. The wireless communication device <NUM> restores the SCG in accordance with the received connection resume message (step <NUM>).

In one embodiment, the SCG is an NR SCG, and the information that is mandatory comprises reconfigurationWithSync. Further, in one embodiment, the MCG is an E-UTRA MCG. In another embodiment, the SCG is an E-UTRA SCG, and the information that is mandatory comprises mobilityControlInfoSCG. Further, in one embodiment, the MCG is an NR MCG.

In regard to restoring the SCG, in one embodiment, resuming the connection to the SCG comprises restoring a stored SCG configuration (step <NUM>-1A) and initiating random access with a PSCell of the restored SCG configuration (step <NUM>-1B). In another embodiment, the connection resume message comprises a delta SCG configuration, and restoring the SCG comprises restoring a stored SCG configuration (step <NUM>-2A), applying the delta SCG configuration on top of the restored SCG configuration to provide an updated SCG configuration (step <NUM>-2B), and initiating random access with a PSCell of the updated SCG configuration (step <NUM>-2C). In another embodiment, the connection resume message comprises a new SCG configuration, and restoring the SCG comprises applying the new SCG configuration (step <NUM>-3A) and initiating random access with a PSCell of the new SCG configuration (step <NUM>-3B).

<FIG> is a schematic block diagram of a radio access node <NUM> according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The radio access node <NUM> may be, for example, a base station <NUM> or <NUM> or a network node that implements all or part of the functionality of the base station <NUM>, eNB, or gNB described herein. As illustrated, the radio access node <NUM> includes a control system <NUM> that includes one or more processors <NUM> (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory <NUM>, and a network interface <NUM>. The one or more processors <NUM> are also referred to herein as processing circuitry. In addition, the radio access node <NUM> may include one or more radio units <NUM> that each includes one or more transmitters <NUM> and one or more receivers <NUM> coupled to one or more antennas <NUM>. The radio units <NUM> may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) <NUM> is external to the control system <NUM> and connected to the control system <NUM> via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) <NUM> and potentially the antenna(s) <NUM> are integrated together with the control system <NUM>. The one or more processors <NUM> operate to provide one or more functions of a radio access node <NUM> as described herein (e.g., one or more functions described herein with respect to <FIG> and <FIG> and any of the other embodiments or example implementations described above). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory <NUM> and executed by the one or more processors <NUM>.

As used herein, a "virtualized" radio access node is an implementation of the radio access node <NUM> in which at least a portion of the functionality of the radio access node <NUM> is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node <NUM> may include the control system <NUM> and/or the one or more radio units <NUM>, as described above. The control system <NUM> may be connected to the radio unit(s) <NUM> via, for example, an optical cable or the like. The radio access node <NUM> includes one or more processing nodes <NUM> coupled to or included as part of a network(s) <NUM>. If present, the control system <NUM> or the radio unit(s) are connected to the processing node(s) <NUM> via the network <NUM>. Each processing node <NUM> includes one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), memory <NUM>, and a network interface <NUM>.

In this example, functions <NUM> of the radio access node <NUM> described herein (e.g., one or more functions described herein with respect to <FIG> and <FIG> and any of the other embodiments or example implementations described above) are implemented at the one or more processing nodes <NUM> or distributed across the one or more processing nodes <NUM> and the control system <NUM> and/or the radio unit(s) <NUM> in any desired manner. In some particular embodiments, some or all of the functions <NUM> of the radio access node <NUM> described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) <NUM>. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) <NUM> and the control system <NUM> is used in order to carry out at least some of the desired functions <NUM>. Notably, in some embodiments, the control system <NUM> may not be included, in which case the radio unit(s) <NUM> communicate directly with the processing node(s) <NUM> via an appropriate network interface(s).

The module(s) <NUM> provide the functionality of the radio access node <NUM> described herein (e.g., one or more functions described herein with respect to <FIG> and <FIG> and any of the other embodiments or example implementations described above).

<FIG> is a schematic block diagram of a wireless communication device <NUM> according to some embodiments of the present disclosure. As illustrated, the wireless communication device <NUM> includes one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), memory <NUM>, and one or more transceivers <NUM> each including one or more transmitters <NUM> and one or more receivers <NUM> coupled to one or more antennas <NUM>. The transceiver(s) <NUM> includes radio-front end circuitry connected to the antenna(s) <NUM> that is configured to condition signals communicated between the antenna(s) <NUM> and the processor(s) <NUM>, as will be appreciated by on of ordinary skill in the art. The processors <NUM> are also referred to herein as processing circuitry. The transceivers <NUM> are also referred to herein as radio circuitry. In some embodiments, the functionality of the wireless communication device <NUM> described above (e.g., one or more functions described herein with respect to <FIG> and any of the other embodiments or example implementations described above) may be fully or partially implemented in software that is, e.g., stored in the memory <NUM> and executed by the processor(s) <NUM>. Note that the wireless communication device <NUM> may include additional components not illustrated in <FIG> such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device <NUM> and/or allowing output of information from the wireless communication device <NUM>), a power supply (e.g., a battery and associated power circuitry), etc..

In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device <NUM> according to any of the embodiments described herein (e.g., one or more functions described herein with respect to <FIG> and any of the other embodiments or example implementations described above) is provided.

The module(s) <NUM> provide the functionality of the wireless communication device <NUM> described herein (e.g., one or more functions described herein with respect to <FIG> and any of the other embodiments or example implementations described above).

Claim 1:
A method performed by a wireless communication device (<NUM>) for resuming a connection after being suspended to a dormant state while the wireless communication device (<NUM>) was operating in dual connectivity with a Master Cell Group, MCG, with a first network node and a Secondary Cell Group, SCG, with a second network node, the method comprising:
receiving (<NUM>) a connection resume message with an indication to restore the SCG of the wireless communication device (<NUM>), the connection resume message comprising information that is mandatory when the connection resume message comprises an indication to restore the SCG, where the information that is mandatory comprises reconfigurationWithSync for an SCG or mobilityControlInfoSCG; and
restoring (<NUM>) the SCG in accordance with the connection resume message.