EP4278843A1

EP4278843A1 - Network nodes, communication devices and methods for handling resume procedure in a wireless communication network

Info

Publication number: EP4278843A1
Application number: EP22702537.6A
Authority: EP
Inventors: Pontus Wallentin; Stefan Wager; Icaro Leonardo DA SILVA; Jens Bergqvist
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2021-01-14
Filing date: 2022-01-10
Publication date: 2023-11-22
Also published as: WO2022154715A1

Abstract

A communication device and method therein are provided for handling a resume procedure from a power saving mode of operation to a connected mode of operation. The communication device is configured with multi-radio connectivity, MR-DC, with a first cell group and a second cell group in a wireless communication network. The communication device initiates (1310) a resume procedure when there is an uplink (UL) data available atthe communication device while it is in the power saving mode of operation and determines (1320) whether a type of the UL data is for a first cell group bearer, a second cell group bearer or a split bearer. The communication device further sets (1330) an UL data indication based on the type of UL data and transmits (1350) the UL data indication to a network node.

Description

NETWORK NODES, COMMUNICATION DEVICES AND METHODS FOR HANDLING

RESUME PROCEDURE IN A WIRELESS COMMUNICATION NETWORK

TECHNICAL FIELD

Embodiments herein relate to network nodes, communication devices and methods therein. In particular, they relate to handling resume procedure for a communication device operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) in a wireless communication network.

BACKGROUND

In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (ST A) and/or user equipments (UE), communicate via a Radio Access Network (RAN) to one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a WiFi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a “NodeB” or “eNodeB” or “gNB”. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless communication device within a range of the radio network node.

A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network or Long Term Evolution (LTE) have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a Fifth Generation (5G) New Radio (NR) network and upcoming releases.

Carrier Aggregation (CA):

CA is used in wireless communication in order to increase bandwidth, and thereby increase the data rate per user, whereby multiple frequency blocks, called component carriers, are assigned to the same user. When CA is configured, the UE only has one Radio Resource Control (RRC) connection with the network node. Further, at RRC connection estabhshment/re-estabhshment/handover, one serving cell provides the Non Access Stratum (NAS) mobility information, and at RRC connection re- establishment/handover, one serving cell provides the security input. This cell is referred to as the Primary Cell (PCell). In addition, depending on UE capabilities, Secondary Cells (SCells) can be configured to form together with the PCell a set of serving cells.

Therefore, when carrier aggregation is configured for the UE, the set of serving cells used by the UE always consists of one PCell and one or more SCells.

The reconfiguration, addition and removal of SCells can be performed by RRC. At intra-Radio Access Technology (intra-RAT) handover, RRC can also add, remove, or reconfigure SCells for usage with the target PCell. When adding a new SCell, dedicated RRC signalling is used for sending all required system information of the SCell i.e. while in connected mode, UEs need not acquire broadcasted system information directly from the SCells.

3GPP Dual Connectivity:

In 3GPP Rel-12, the LTE feature Dual Connectivity (DC) was introduced, to enable the UE to be connected in two cell groups, each controlled by an LTE access node, eNBs, labelled as the Master eNB (MeNB) and the Secondary eNB (SeNB). The UE still only has one RRC connection with the network node. In 3GPP, the Dual Connectivity (DC) solution has since then been evolved and is now also specified for NR as well as between LTE and NR. With introduction of 5G, the term Multi-Radio Dual Connectivity (MR-DC), see also 3GPP TS 37.340, was defined as a generic term for all dual connectivity options which includes at least one NR access node. Using the MR-DC generalized terminology, the UE is connected in a Master Cell Group (MCG), controlled by the Master Node (MN), and in a Secondary Cell Group (SCG) controlled by a Secondary Node (SN).

Further, in MR-DC, when dual connectivity is configured for the UE, within each of the two cell groups, MCG and SCG, carrier aggregation may be used as well. In this case, within the MCG, controlled by the master node (MN), the UE may use one PCell and one or more SCell(s). And within the SCG, controlled by the secondary node (SN), the UE may use one Primary SCell (PSCell), also known as the primary SCG cell in NR, and one or more SCell(s). This combined case, i.e. dual connectivity combined with carrier aggregation in MR-DC, is illustrated in Figure 1, where a MN 110, a SN 120, a UE 130, MCG 140, SCG 150, a PCell 160 in MCG 140, a PSCell 170 in the SCG 150, and multiple SCells are shown. In NR, the primary cell of a master or secondary cell group is sometimes also referred to as the Special Cell (SpCell). Hence, the SpCell in the MCG is the PCell and the SpCell in the SCG is the PSCell.

There are different ways to deploy 5G network with or without interworking with LTE, also referred to as E-UTRA and evolved packet core (EPC). In principle, NR and LTE can be deployed without any interworking, denoted by NR stand-alone (SA) operation, also known as Option 2, that is gNB in NR can be connected to 5G core network (5GC) and eNB in LTE can be connected to EPC with no interconnection between the two, also known as Option 1.

On the other hand, the first supported version of NR uses dual connectivity, denoted as EN-DC (E-UTRAN-NR Dual Connectivity), also known as Option 3, as depicted in Figure 2. In such a deployment, dual connectivity between NR and LTE is applied, where a UE 210 is connected both to an LTE access node LTE MeNB 220 with the LTE radio interface LTE Uu 221 and to an NR access node NR SgNB 230 with the NR radio interface NR Uu 231. Further, in EN-DC, the LTE access node acts as the master node, in this case known as the Master eNB (MeNB), controlling the master cell group (MCG), and the NR access node acts as the secondary node, in this case sometimes also known as the Secondary gNB (SgNB), controlling the secondary cell group (SCG). The SgNB may not have a control plane connection to the core network EPC 240 which instead is provided by MeNB and in this case the NR. This is also called as “Non-standalone NR" or, in short, "NSA NR". Notice that in this case the functionality of an NR cell is limited and would be used for connected mode UEs as a booster and/or diversity leg, but an UE in RRCJDLE state in which the UE is switched on but does not have any established RRC connection, cannot camp on these NR cells.

With introduction of 5GC, other options may be also valid. As mentioned above, option 2 supports stand-alone NR deployment where gNB is connected to 5GC. Similarly, LTE can also be connected to 5GC using option 5, also known as eLTE, E-UTRA/5GC, or LTE/5GC and the node can be referred to as an ng-eNB. In these cases, both NR and LTE are seen as part of the NG-RAN and both the ng-eNB and the gNB can be referred to as NG-RAN nodes.

It is worth noting that, there are also other variants of dual connectivity between LTE and NR which have been standardized as part of NG-RAN connected to 5GC. Under the MR-DC umbrella, we have:

• EN-DC (Option 3): LTE is the master node and NR is the secondary node (EPC CN employed, as depicted in Figure 2). • NE-DC (Option 4): NR is the master node and LTE is the secondary (5GCN employed).

• NGEN-DC (Option 7): LTE is the master node and NR is the secondary (5GCN employed).

• NR-DC (variant of Option 2): Dual connectivity where both the master node (MN) controlling the MCG, and the secondary node (SN) controlling the SCG, are NR (5GCN employed, as depicted in Figure 3).

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 e.g. there could be eNB base station supporting option 3, 5 and 7 in the same network as NR base station supporting 2 and 4. In combination with dual connectivity solutions between LTE and NR it is also possible to support CA (Carrier Aggregation) in each cell group, i.e. MCG and SCG and dual connectivity between nodes on same RAT, e.g. NR-NR DC. For the LTE cells, a consequence of these different deployments is the co-existence of LTE cells associated to eNBs connected to EPC, 5GC or both EPC and 5GC.

As said earlier, DC is standardized for both LTE and E-UTRA -NR DC (EN-DC).

LTE DC and EN-DC are designed differently when it comes to which nodes control what. Basically, there are two options:

1) Centralized solution, like LTE-DC,

2) Decentralized solution, like EN-DC.

Figure 4 shows the schematic control plane architecture looks like for LTE DC, EN- DC and NR-DC. The main difference here is that in EN-DC and NR-DC, the SN has a separate NR RRC entity. This means that the SN can control the UE also; sometimes without the knowledge of the MN but often the SN need to coordinate with the MN. In LTE-DC, the RRC decisions are always coming from the MN, i.e. MN to UE. Note however, the SN still decides the configuration of the SN, since it is only the SN itself that has knowledge of what kind of resources, capabilities etc. it has.

For EN-DC and NR-DC, the major changes compared to LTE DC are:

• The introduction of split data radio bearer (DRB) from the SN (known as SN terminated split DRB).

• The introduction of split signaling radio bearer (SRB) for RRC.

• The introduction of a direct SRB from the SN (also referred to as SCG SRB or SRB3).

Figure 5 shows, from network node perspective, the user plane protocol architecture in MR-DC with EPC (EN-DC). In this case, the network node can configure either E-UTRA Packet Data Convergence Protocol (PDCP) or NR PDCP for MN terminated MCG DRBs while NR PDCP is always used for all other DRBs.

Figure 6 shows, from network node perspective, the user plane protocol architecture in MR-DC with 5GC (NGEN-DC, NE-DC and NR-DC). In MR-DC with 5GC, NR PDCP is always used for all Data Radio Bearer (DRB) types. In NGEN-DC, E-UTRA Radio Link Control/Medium Access Control (RLC/MAC) is used in the MN while NR RLC/MAC is used in the SN. In NE-DC, NR RLC/MAC is used in the MN while E-UTRA RLC/MAC is used in the SN. In NR-DC, NR RLC/MAC is used in both MN and SN.

Packet duplication:

Packet data convergence protocol (PDCP) packet duplication, also known as Packet Duplication or PDCP duplication, is a feature that can be used to support ultrareliable low latency (URLLC) use-cases.

PDCP duplication is configurable in both carrier aggregation (CA) as well as dual connectivity (DC),

According to 3GPP TS 38.300 v16.1 , and depicted in Figure 7, when duplication is configured for a radio bearer by RRC, at least one secondary RLC entity is added to the radio bearer to handle the duplicated PDCP Protocol Data Units (PDUs), where the logical channel corresponding to the primary Radio link control (RLC) entity is referred to as the primary logical channel, and the logical channel corresponding to the secondary RLC entity(ies), the secondary logical channel(s).

Duplication at PDCP therefore consists in submitting the same PDCP PDUs multiple times: once to each activated RLC entity for the radio bearer. The packet duplicates are transmitted via the different carriers (cells). With multiple independent transmission paths, packet duplication therefore increases reliability and reduces latency and is especially beneficial for URLLC services.

When configuring duplication for a DRB, RRC also sets the state of PDCP duplication, either activated or deactivated, at the time of configuration or reconfiguration. After the configuration, the PDCP duplication state can then be dynamically controlled by means of a MAC control element and in DC, the UE applies the MAC CE commands regardless of their origin, MCG or SCG.

SCG power saving mode:

In order to improve network energy efficiency and UE battery life for UEs in MR-DC, a Rel-17 work item is planned to introduce efficient SCG/SCell activation/deactivation. This can be especially important for MR-DC configurations with NR SCG, as it has been evaluated in 3GPP contribution document RP-190919 that in some cases NR UE power consumption is 3 to 4 times higher than LTE.

3GPP has specified the concepts of dormant SCell (in LTE) and dormancy like behavior of an SCell (for NR).

In LTE, when an SCell is in dormant state, like in the deactivate state, the UE does not need to monitor the corresponding Physical Downlink Control Channel (PDCCH) or PDSCH and cannot transmit in the corresponding uplink. However, differently from deactivated state, the UE is required to perform and report Channel Quality Indicator (CQI) measurements. A PUCCH SCell, i.e. SCell configured with PUCCH, cannot be in dormant state.

In NR, dormancy like behaviour for SCells is realized using the concept of dormant Bandwidth Parts (BWPs). See Figure 8, an Illustration of dormancy like behavior for SCells in NR. One dormant BWP, which is one of the dedicated BWPs configured by the network node via RRC signaling, can be configured for an SCell. If the active BWP of the activated SCell is a dormant BWP, the UE stops monitoring PDCCH on the SCell but continues performing Channel State Information (CSI) measurements, Automatic Gain Control (AGC) and beam management, if configured. A Downlink Control Information (DCI) is used to control entering/leaving the dormant BWP for one or more SCell(s) or one or more SCell group(s), and it is sent to the special cell (SpCell) of the cell group that the SCell belongs to, i.e. PCell in case the SCell belongs to the MCG and PSCell if the SCell belongs to the SCG. The SpCell, i.e. PCell of PSCell, and PUCCH SCell cannot be configured with a dormant BWP.

However, only SCells can be put in dormant state (in LTE) or operate in dormancy like behavior (NR). Also, only SCells can be put into the deactivated state in both LTE and NR. Thus, if the UE is configured with MR-DC, it is not possible to fully benefit from the power saving options of dormant state or dormancy like behavior as the PSCell cannot be configured with that feature. Instead, an existing solution could be releasing for power savings and adding when traffic demands requires the SCG on a need basis. However, traffic is likely to be bursty, and adding and releasing the SCG involves a significant amount of RRC signaling and inter-node messaging between the MN and the SN, which causes considerable delay.

In 3GPP rel-16, some discussions were made regarding putting also the PSCell in dormancy, also referred to as SCG Suspension. Some preliminary agreements were made in RAN2-107bis, Oct 2019 (see chairman notes at R2-1914301): R2-1914301 assumes the following (can be slightly modified due to progress on Scell dormancy):

=> The UE supports network-controlled suspension of the SCG in RRC_CONNECTED.

=> UE behavior for a suspended SCG is FFS

=> The UE supports at most one SCG configuration, suspended or not suspended, in Rel16.

=> In RRC_CONNECTED upon addition of the SCG, the SCG can be either suspended or not suspended by configuration.

In RAN2-108, further discussion was made to clarify the above for further studies (FFSs).

Some solutions have been proposed in Rel-16, but these have different problems. For example, in R2-1908679 (Introducing suspension of SCG - Qualcomm) the paper proposes that gNB can indicate UE to suspend SCG transmissions when no data traffic is expected to be sent in SCG so that UE keeps the SCG configuration but does not use it for power saving purpose. Therein, it is mentioned that signaling to suspend SCG could be based on DCI/MAC-CE/RRC signaling, but no details were provided regarding the configuration from the gNB to the UE. And, differently from the defined behavior for SCell(s), PSCell(s) may be associated to a different network node, e.g. a gNodeB operating as Secondary Node.

The 3GPP discussions on solutions for the Rel-17 MR-DC work item objective "Support efficient activation/de-activation mechanism for one SCG and Scells" have just started in 3GPP RAN 1 , RAN2 and RAN3. As part of this objective, the concept of a "deactivated SCG" with aim of power saving when the traffic demands are dynamically reduced is being discussed. As Figure 9 also illustrates, there are two SCG states, sometimes referred to as states for SCG activation, being discussed, here referred to as "SCG deactivated state" and "SCG activated state". These states concern the power saving mode for the SCG and should not be confused with the RRC states.

Current RAN2 assumption is that during “SCG deactivated state” or sometimes referred to as "SCG is deactivated", in order to save power, the UE does not perform PDCCH monitoring of the PSCell. This also means that Uplink/Downlink (UL/DL) data transmission in the SCG is suspended when the SCG is in SCG deactivated state. Activation and deactivation of the SCG is typically controlled by the network node, e.g. by the MN, using RRC signalling. Moreover, RAN2 has agreed that PSCell mobility is supported while the SCG is deactivated, even if details are for further studies (FFS). When the UE is configured with the SCG in "SCG activated state" the power saving of the SCG is not applied. RRCJNACTIVE and Suspend/ Resume procedures:

Figure 10 Illustrates the RRC states in NR specified in 3GPP TS 38.331 v16.2.0.

A UE is either in RRC_CONNECTED state or in RRCJNACTIVE state, the latter is also known as suspended state, when an RRC connection has been established. If this is not the case, i.e. no RRC connection is established, the UE is in RRCJDLE state.

When the UE in RRC_CONNECTED state receives an RRC Release with a suspend configuration (suspendConfig in RRCRelease) the UE transitions to RRCJNACTIVE state and stores its configuration in the so called AS Inactive context. Then, when the UE tries to resume the configuration is restored so that network node is able to apply delta signaling in the RRCResume message during a resume procedure.

Figure 11 illustrates the RRC procedure to resume a suspended RRC connection. The details of this procedure are specified in 3GPP TS 38.331 v16.2.0.

In the particular case the RRC_CONNECTED UE is configured with MR-DC, e.g. has a configured SCG, there are some differences in suspend/resume procedures in 3GPP Release 15 and Release 16.

The network node may determine to suspend an RRC connection for a UE operating in MR-DC, e.g. configured with a Secondary Cell Group (SCG) and with a Master Cell Group (MCG), so the UE transitions from RRC_CONNETED to RRCJNACTIVE. In Rel-15, it was defined that the UE releases MR-DC configurations upon entering RRCJNACTIVE (though it was rather modeled as an MR-DC release upon the initiation to resume defined in TS 38.331 , 5.3.13.2), see section 5.3.8.3 Reception of the RRCRelease by the UE, section 5.3.13 RRC connection resume and section 5.3.5.10 MR-DC release in Rel-15 for detail information.

In Rel-16 an enhancement was introduced: for a UE operating in MR-DC, e.g. EN- DC, NR-DC, that is suspended to RRCJNACTIVE, the UE stores the SCG configurations, at least some of the configurations, so that these can be restored and resumed upon resume procedure. Among the changes introduced in 5.3.8.3, the UE in Rel-16 stores the spCellConfigCommon within ReconfigurationWithSync oi the NR PSCell (if configured).

Another change introduced in resume initiation in Rel-16 for this feature was that the UE only releases MR-DC if it does not support maintaining SCG configuration upon connection resumption. And, when the UE restores the context it restores the MR-DC configuration, including the SCG configuration (as defined up to Rel-16).

Yet another change is that RRCResume can include the field mrdc- SecondaryCellGroup possibly set to nr-SCG, so that an SCG RRC Reconfiguration can include the reconfiguration with sync for the SCG to be resumed (or added/ modified). This is needed for the UE to trigger a random access procedure with the PSCell that is being resumed. See section 5.3.8.3 Reception of the RRCRelease by the UE and section 5.3.13 RRC connection resume comprising section 5.3.13.1 General, 5.3.13.2 Initiation, section 5.3.13.3 Actions related to transmission of RRCResumeRequest or RRCResumeRequestl message and section 5.3.13.4 Reception of the RRCResume by the UE in Rel-16 for detail information.

With the introduction in 3GPP Rel-17 of the SCG power saving mode, often called in 3GPP "deactivated SCG" or "SCG deactivated state", as described above, the network node may still determine to suspend the UE to RRCJNACTIVE while the SCG is deactivated. Upon suspension, i.e. reception of an RRCRelease with suspendConfig, if the SCG is activated the same behavior as in Rel-16 could be adopted, as to some extent, in Rel-16 the SCG is always activated when an SCG is configured. With the introduction of the Rel-17 feature, the SCG may be deactivated when the UE receives an RRCRelease with suspendConfig and transitions to RRC NACTIVE. And, regardless if the UE was suspended when it was configured with multi-radio dual connectivity (MR-DC) including a Master Cell Group (MCG) and a Secondary Cell Group (SCG), when the UE resumes from RRCJNACTIVE to RRC_CONNECTED it has been agreed in 3GPP RAN2 that the SCG state, e.g. SCG activated state or SCG deactivated state, can be configured at RRC resume. In legacy, when the UE resumes e.g. due to the fact there is some uplink traffic, NAS layer trigger the resume procedure and a cause value mo-Data is set to be included in RRC Resume Request message, as follows: 5.3.13 RRC connection resume 5.3.13.1 General

L)E | I Network

Figure 5.3.13.1-1 : RRC connection resume, successful

[...]

The purpose of this procedure is to resume a suspended RRC connection, including resuming SRB(s) and DRB(s) or perform an RNA update. [■ ■ ■ ]

5.3.13.2 Initiation

The UE initiates the procedure when upper layers or AS (when responding to RAN paging, upon triggering RNA updates while the UE is in RRC INACTIVE, or for sidelink communication as specified in sub-clause 5.3.13.1a) requests the resume of a suspended RRC connection.

The UE shall ensure having valid and up to date essential system information as specified in clause

5.2.2.2 before initiating this procedure.

Upon initiation of the procedure, the UE shall:

1> if the resumption of the RRC connection is triggered by response to NG-RAN paging:

2> select 'O' as the Access Category;

2> perform the unified access control procedure as specified in 5.3.14 using the selected Access Category and one or more Access Identities provided by upper layers;

3> if the access attempt is barred, the procedure ends;

1> else if the resumption of the RRC connection is triggered by upper layers:

2> if the upper layers provide an Access Category and one or more Access Identities:

3> perform the unified access control procedure as specified in 5.3. 14 using the Access Category and Access Identities provided by upper layers;

4> if the access attempt is barred, the procedure ends;

2> set the resumeCause in accordance with the information received from upper layers;

[...]

RRCResumeRequest message

— ASN1 START

— TAG-RRCRESUMEREQUEST-START

RRCResumeRequest : : = SEQUENCE { rrcResume Request RRC Resume Request- IE s

}

RRCResumeRequest-IEs : : = SEQUENCE { resume Identity Shortl-RNTI-Value , resumeMAC-I BIT STRING ( SIZE ( 16 ) ) , resumeCause ResumeCause , spare BIT STRING ( SIZE ( 1 ) )

}

— TAG-RRCRESUMEREQUEST-STOP

— ASN1STOP

[...]

— Resume Cause

The IE ResumeCause is used to indicate the resume cause in RRCResumeRequest and RRCResumeRequestl .

ResumeCause information element

— ASN1 START

— TAG-RESUMECAUSE-START ResumeCause : : = ENUMERATED { emergency, highPriorityAccess , mt-Access , mo-Signallin , mo-Data , mo-VoiceCall , mo- VideoCall , mo-SMS , rna-Update , mps -PriorityAccess , mcs -Prior ityAcces s , spare l , spare2 , spare3 , spare4 , spare5 }

— TAG-RESUMECAUSE-STOP

— ASN1STOP In the following, the terms “suspended SCG”, “SCG in power saving mode”, “SCG deactivated state”, or “deactivated SCG” are used interchangeably. The term “suspended SCG” may also be called as “deactivated SCG or inactive SCG”, or “dormant SCG”. The terms “resumed SCG”, “SCG in normal operating mode”, “SCG activated state” and “SCG in non-power saving mode” are used interchangeably. The terms “resumed SCG” may also be called as “activated SCG” or “active SCG”. The operation of the SCG operating in resumed or active mode may also be called as normal SCG operation or legacy SCG operation. Examples of operations are UE signal reception/transmission procedures e.g. reception of signals messages, transmission of signals messages, etc. The terms “communication device” and “UE” are used interchangeably. The term “network node”, “gNB”, “eNB”, “gNodeB are used interchangeably.

SUMMARY

As part of developing embodiments herein problems were identified and will first be discussed. Even though upon reception the network node knows that the UE requested the resume procedure due to the need to have UL transmission, during RRC resume of the UE, the network node is not aware whether the UE initiated RRC resume request was triggered due to uplink data for a MCG DRB or for an SCG DRB. As a matter of fact, that remains unknown even after context fetching, which enables the network node, e.g. the target network node where the UE is trying to resume, to at least know whether the UE was configured with an SCG or split DRB.

This means that the network node would not be aware of which SCG state or mode of operation to select, e.g. SCG activated state or SCG deactivated state, for the UE performing RRC resume procedure. Hence, the network node, e.g. target gNodeB where the UE tries to resume, may activate the SCG unnecessarily, in case UL data that triggered the resume request is associated to the MCG or the amount of data is not sufficient to justify activating the SCG. When the network node realizes that sub-optimal decision, the network node would have to transmit another message to the UE after the resume procedure, e.g. an RRCReconfiguration and/or a MAC CE, to deactivate the SCG for power savings purpose. During the time the UE has resumed until the time the UE receives this message, more power is consumed and more signaling is used after resume. Alternatively, the network node, e.g. target gNodeB where the UE tries to resume, may deactivate the SCG even though the UE has UL data associated to the SCG. In that case the network node would then have to transmit another message to activate the SCG after the RRC resume procedure once it realizes that there is data associated to the SCG that justifies activation of the SCG. During the time the UE has resumed until the time the UE receives this message, the performance would then be restricted due to that only the MCG can be used.

In order to resume a stored SCG as part of the RRC Resume procedure, i.e. already with the RRC Resume message or shortly thereafter, the network node has to do it more or less blindly. This is since the network node has then not received any new measurement results from the UE for the SCG (PSCell) that it can use to determine if the UE is in radio coverage of the SCG/PSCell. There is then a risk that the UE is configured with the SCG even if it is out-of-coverage of the previous SCG/PSCell. Therefore, it is an object of embodiments herein to provide an improved method for handling a resume procedure for a communication device operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) of a network node in a wireless communication network.

According to one aspect of the embodiments herein, the object is achieved by a method performed in a communication device for handling a resume procedure from a suspended state to a connected state. The communication device is configured with multiradio connectivity (MR-DC) with a Master Cell Group (MCG) and a Secondary Cell Group (SCG). The communication device initiates a resume procedure when there is uplink data available. The communication device determines the type of the UL data, i.e. whether the UL data is available for an MCG bearer, an SCG bearer or a split bearer. The communication device sets an UL data indication based on the determination of whether the UL data is available for an MCG bearer, an SCG bearer or a split bearer. The communication device sends the UL data indication to a network node. The UL data indication may be one of a resume cause, a selection of Physical Random Access Channel (PRACH) resource such as a preamble, an assistance information message or an information element in the RRC Resume Complete message. The UL data indication may indicate whether the resume is initiated due to uplink data that is available for the MCG or for the SCG. The UL data indication may be a value representing the amount of available data volume for the MCG or SCG.

In other words, the communication device sends to a network node upon resuming from the suspended state such as RRCJNACTIVE state to the connected state such as RRC_CONNECTED state, an UL data indication for assisting the network node to determine a SCG configuration for the communication device. When the UL data is available, the resume from a suspended state is performed, the communication device determines whether the UL data is for an MCG, SCG or split DRB and sets the UL data indication based on this determination and possibly other criteria such as a data volume threshold.

According to one aspect of the embodiments herein, the object is achieved by a method performed in a network node, such as a gNB, to determine a SCG configuration upon a communication device initiating a resume procedure from a suspended state such as RRCJNACTIVE state to a connected state such as RRC_CONNECTED state, based on an UL data indication, SCG coverage indication or a measurement report received from the communication device. The network node is configured to: Determine whether a suspend SCG is to be resumed and, if it is to be resumed, which mode of operation should be set to the SCG e.g. deactivated or activated;

Determine whether an SCG is to be released in case the communication device trying to resume is configured with an SCG;

Determine whether an SCG is to be added in case the communication device trying to resume is not configured with an SCG, and, if it is to be added, which mode of operation should be set to the SCG e.g. deactivated or activated.

According to one aspect of the embodiments herein, the object is achieved by a method performed in a communication device in RRCJNACTIVE state to initiate measurements for the SCG, e.g. PSCell, that it has stored as part of the UE Inactive AS Context when the communication device determines that it has UL data available for the SCG, such as an SCG DRB or sufficient amount of data available for a split DRB to justify SCG activation.

The embodiments herein enable the network node to select strategy for a communication device in MR-DC during resuming from a suspended state, for example, to select the SCG state, e.g. SCG deactivated state or SCG activated state.

In some embodiments, a benefit of the embodiment herein is that the network node may set the SCG state in the first RRC message such as an RRCResume RRC message responding to the resume request.

Thanks to the method according to embodiments herein, the network node, e.g. the target network node the communication device is trying to resume to, is made aware whether the communication device initiated RRC resume request was triggered due to uplink data for a MCG DRB or for an SCG DRB, and based on that, take the appropriated educated decision on setting up MR-DC, release MR-DC, resume MR-DC and in case of setup and resume, in which state or mode of operation the SCG should be e.g. deactivated SCG or activated SCG.

Hence, the network node, e.g. the target gNodeB where the communication device tries to resume, would not activate the SCG unnecessarily, in case the UL data that triggered the resume request is associated to the MCG or the amount of data is not sufficient to justify activating the SCG, which prevents unnecessary actions on the SCG and prevents unnecessary spent of energy at the communication device. That translates in lower power consumption at the communication device thanks to the method according to embodiments herein. In addition to it, by preventing a potentially sub-optimal decision, the network node does not need to transmit another message to the communication device after the resume procedure e.g. an RRCReconfiguration and/or a MAC CE to deactivate the SCG for power savings purpose, which is also a signaling reduction.

Therefor embodiments herein provide an improved method for handling a resume procedure for a communication device operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) of a network node in a wireless communication network.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail with reference to attached drawings in which:

Figure 1 is a schematic block diagram illustrating dual connectivity combined with carrier aggregation in MR-DC;

Figure 2 is a schematic block diagram illustrating E-UTRAN-NR Dual Connectivity;

Figure 3 is a schematic block diagram illustrating a NR-DC, where both the master node controlling the MCG and the secondary node controlling the SCG are NR;

Figure 4 is a schematic block diagram illustrating Control Plane architecture for Dual Connectivity in LTE DC, EN-DC and NR-DC;

Figure 5 is a schematic block diagram illustrating network side protocol termination options for MCG, SCG and split DRBs in MR-DC with EPC (EN-DC);

Figure 6 is a schematic block diagram illustrating network side protocol termination options for MCG, SCG and split DRBs in MR-DC with 5GC (NGEN-DC, NE- DC and NR-DC);

Figure 7 is a schematic block diagram illustrating packet duplication;

Figure 8 is a schematic block diagram illustrating dormancy like behavior for SCells in

NR;

Figure 9 is a schematic block diagram illustrating SCG states in 3GPP Rel-17;

Figure 10 is a schematic block diagram illustrating UE state machine and state transitions in NR;

Figure 11 is a signaling diagram illustrating RRC connection resume procedure, a successful case;

Figure 12 is a schematic block diagram illustrating a wireless communication network; Figure 13 is a flow chart illustrating an example embodiment of a method performed in a communication device according to embodiments herein;

Figure 14 is a signaling diagram illustrating an example embodiment of a resume procedure according to embodiments herein;

Figure 15 is a signaling diagram illustrating another example embodiment of a resume procedure according to embodiments herein;

Figure 16 is a signaling diagram illustrating another example embodiment of a resume procedure according to embodiments herein;

Figure 17 is a flow chart illustrating another example embodiment of a method performed in a communication device according to embodiments herein;

Figure 18 is a flow chart illustrating an example embodiment of a method performed in a network node according to embodiments herein;

Figure 19 is a flow chart illustrating another example embodiment of a method performed in a network node according to embodiments herein;

Figure 20 is a schematic block diagram illustrating an example embodiment of a network node; and

Figure 21 is a schematic block diagram illustrating an example embodiment of a communication device.

DETAILED DESCRIPTION

Embodiments herein relate to communications networks in general. Figure 12 is a schematic overview depicting a communication network 1200. The communication network 1200 may be a wireless communications network comprising one or more RANs, and one or more CNs. The communication network 1200 may use a number of different technologies, such as Wi-Fi, Long Term Evolution (LTE), LTE-Advanced, NR, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations.

In the wireless communication network 1200, one or more wireless communication devices 1230, 1231 such as a UE, a mobile station or a wireless terminals communicates via one or more Radio Access Networks (RAN) to one or more core networks (CN). It should be understood by the skilled in the art that “wireless communication device” is a non-limiting term which means any terminal, wireless communication terminal, user equipment, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell.

Network nodes operate in the wireless communication network 1200 such as a first network node 1211 and a second network node 1212. The first and second network node 1211 , 1212 may be any of RAN node, such as gNB, eNB, en-gNB, ng-eNB, gNB etc. The first network node 1211 provides radio coverage over a geographical area, a service area 11 , which may also be referred to as a beam or a beam group where the group of beams is covering the service area of a first radio access technology (RAT), such as 5G, LTE, Wi-Fi or similar. The second network node 1212 provides radio coverage over a geographical area, a service area 12, which may also be referred to as a beam or a beam group where the group of beams is covering the service area of a first or a second radio access technology (RAT), such as 5G, LTE, Wi-Fi or similar. It should be noted that a network node may be a RAN node, a CN node or an GAM node.

The first and second network nodes 1211 and 1212 may be a transmission and reception point e.g. a radio access network node such as a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, a gNB, an evolved Node B (eNB, eNode B), a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of communicating with a wireless communication device within the service area served by the respective first and second network nodes 1211 and 1212 depending e.g. on the radio access technology and terminology used. The first and second network nodes 1211 and 1212 may be referred to as a source and target network node, respectively, and may communicate with the wireless communication device 1230, 1231 with Downlink (DL) transmissions to the wireless communication device 1230, 1231 and Uplink (UL) transmissions from the wireless communication device 1230, 1231.

The first and second network nodes 1211 , 1212 may each be either a master node (MN) having a cell group MCG, or a secondary node (SN) having a cell group SCG, respectively, as shown in Figure 1.

The description herein describes terms like SCG and PSCell, as one of the cells associated with the SCG. That can be for example a PSCell as defined in NR specifications (e.g. RRC TS 38.331), defined as a Special Cell (SpCell) of the SCG, or a Primary SCG Cell (PSCell), as follows: - Secondary Cell Group: For a UE configured with dual connectivity, the subset of serving cells comprising of the PSCell and zero or more secondary cells (SCells).

- Special Cell: For Dual Connectivity operation the term Special Cell refers to the PCell of the MCG or the PSCell of the SCG, otherwise the term Special Cell refers to the PCell.

- Primary SCG Cell (PSCell): For dual connectivity operation, the SCG cell in which the UE performs random access when performing the Reconfiguration with Sync procedure.

For the sake of brevity, the description herein mostly refers and shows examples wherein the second cell group is a Secondary Cell Group (SCG) that is deactivated or suspended or in power saving mode of operation, for a UE configured with Multi-Radio Dual Connectivity (MR-DC). However, the method is equally applicable for the case where the second cell group is a Master Cell Group (MCG) for a UE configured with Dual Connectivity (e.g. MR-DC), wherein the MCG could be suspended, while the SCG is operating in normal mode.

The description herein describes that when the second cell group is deactivated e.g. SCG becomes deactivated upon reception of an indication from the network node, the UE stops monitoring PDCCH on the SCG cells, i.e. stop monitoring PDCCH of the PSCell and of the SCells of the SCG. Solutions are mainly described using as an example a second cell group that is a Secondary Cell Group that the UE configured with MR-DC is configured with; and, the SCG being deactivated mode of operation at the UE when the UE perform the actions disclosed in the method. However, the method is also applicable for the case one assumes that the second cell group is a Master Cell Group (MCG) that is deactivated, so that the UE stops monitoring PDCCH on the MCG and continues monitoring PDCCH on the SCG.

Correspondingly, the description herein mostly refers and shows examples wherein the first cell group is a Master Cell Group (MCG) for a UE configured with Multi-Radio Dual Connectivity (MR-DC). However, the method is equally applicable for the case where the first cell group is a Secondary Cell Group (SCG) that is deactivated or suspended or in power saving mode of operation, for a UE configured with Multi-Radio Dual Connectivity (MR-DC).

According to embodiments herein, a method performed by a communication device

1230 is provided for handling a resume procedure from a first state to a second state. The first state may be a suspended state such as RRCJNACTIVE state, the second state may be a connected state such as RRC_CONNECTED state.

According to some embodiments herein, the method comprises sending an UL data indication indicating whether the resume procedure is initiated due to uplink data that is available for the MCG, such as an MCG DRB, or for the SCG, such as an SCG DRB, or whether sufficient data is available for a split DRB to justify SCG activation. According to embodiments herein, the communication device 1230 may have been suspended while it was configured with the MCG and SCG.

In this embodiments, the communication device 1230 determines whether the resume procedure is initiated due to uplink data that is available for the MCG, such as an MCG DRB, or for the SCG, such as an SCG DRB or whether sufficient amount of data e.g. determined based on a configured threshold for UL data volume, is available for a split DRB to justify SCG activation. Based on this determination the communication device 1230 includes the UL data indication during the resume procedure e.g. within a resume request to the network node 1211 and/or multiplexed with the resume request to the network node 1211.

The method will be described in detail with reference to Figure 13, where the main actions or steps performed by the communication device 1230 according to a first embodiment is illustrated. The method comprises the following actions which action may be performed in any suitable order.

Action 1310

The communication device 1230 is in a first state e.g. a suspended state such as the RRCJNACTIVE state, and has MR-DC configured with an MCG and an SCG. When uplink data becomes available, upper layers triggers the RRC layer in the communication device 1230 to initiate resume of the suspended RRC connection.

Action 1320

The communication device 1230 determines whether the UL data is for an MCG, SCG or split DRB.

Action 1330

The communication device 1230 sets an UL data indication based on the determined whether the UL data is for an MCG, SCG or split DRB.

The communication device 1231 sets the UL data indication to "MCG" if the UL data is for an MCG DRB.

The communication device 1230 sets the UL data indication to "SCG" if the UL data is for an SCG DRB. Action 1340

If the UL data is for a split DRB, the communication device 1230 may further determine if the amount of the UL data exceeds a threshold.

The communication device 1230 sets the UL data indication to “SCG” if the amount of data exceeds a network configured threshold value. Otherwise the UL data indication is set to “MCG”.

Action 1350

The communication device 1230 initiates a resume procedure by transmitting a resume request, e.g. RRC Resume Request message to a network node, e.g. the network node 1211. During the resume procedure, the communication device 1230 also transmits the UL data indication. The communication device 1230 may include the UL data indication during the resume procedure e.g. within the resume request to the network node 1211 and/or multiplexed with the resume request to the network node 1211.

Concerning how the UL data indication is indicated to the network node 1211 , there may be different alternatives.

In one alternative, as illustrated in Figure 14, during the resume procedure, the UL data indication may, for example, be transmitted as a resume cause, which may be a parameter set in the RRC Resume Request message that the UE transmits to a network node MN/gNB that the UE tries to resume. For example, a new resume cause e.g. scg-data, is set to indicate that the resume procedure has been triggered due to a certain amount of data mapped to an SCG bearer or split bearer being above a predetermined threshold. And for example, in other cases such as when the UL data is for an MCG bearer, the UE sets the value of the existing resume cause "mo-data", or another existing resume cause. In another embodiment, a new cause value may indicate that the UE has an amount of UL data in buffer above a certain threshold regardless of that being associated to SCG bearers.

In another embodiment, as illustrated in Figure 15, the UL data indication is indicated to the network node e.g. MN/gNB that UE tries to resume by the selection of a specific PRACH resource, such as a preamble e.g. that may be associated to a preamble group and/or a specific time-frequency PRACH resource that according to a random access configuration indicates the UL data indication. For example, the network node could have configured a preamble group for indicating UL traffic above a threshold so that the UE that wants to resume determines if UL data in buffer is above the threshold and if it is, it selects a preamble associated to that group so that upon reception at the network node, the network node becomes aware that the UE has an amount of UL data in buffer above the threshold. In an alternative, the UL data indication is associated to data to be transmitted by an SCG, e.g. data mapped to an SCG bearer, so that it not only indicates to the network node that an amount of data is above a threshold, but that the amount of data is for an SCG transmission. Another alternative is to define multiple preamble groups indicating different indications e.g. group X1 data for both MCG and SCG, group X2 data for the SCG only, group X3 data for the MCG only. In one example, the network node provides the configuration for PRACH resource(s), e.g. preamble(s) and/or specific timefrequency PRACH resource(s) to use for UL data indication in system information. In another example, the network node provides the configuration in dedicated signaling, such as the RRC Release message that suspended the U to RRCJNACTIVE state.

In another embodiment, as illustrated in Figure 16, the UL data indication may be indicated in an assistance information message e.g. UEAssistancelnformation, via RRC that can be multiplexed with an RRC Resume Request and/or multiplexed with an RRC Resume Complete and/or transmitted after the UE transmits the RRC Resume Complete message or an information element in the RRC Resume Complete message.

In the examples above, the UL data threshold could be the same as configured for PDCP (for the associated bearer) or a threshold configured via system information, or another threshold for that specific purpose provided in RRC release when the UE was suspended to INACTIVE state.

In one example, the UL data indication is a binary with two values, each representing whether the resume procedure was initiated due to uplink data that is available for the MCG, such as an MCG DRB, or whether the resume request was initiated due to uplink data that is available for the SCG, such as an SCG DRB or sufficient amount of data available for a split DRB to justify SCG activation.

In another example, the UL data indication also includes a data volume value representing the amount of uplink data that is available for the MCG, such as an MCG DRB or a set of MCG DRBs, or for the SCG, such as an SCG DRB, or a set of SCG DRBs or for a split DRB. In one example, the data volume value for the split DRB or DRBs is reported separately from the two values for MCG and SCG. In another example, the data volume value of the split DRB or split DRBs is added to the data volume value of the MCG and SCG, and only MCG and SCG values are signaled to the network node. According some embodiments herein, a method performed by a communication device 1230 is provided for handling a resume procedure from a first state, e.g. a suspended state to a second state, e.g. a connected state, which may be combined with the first embodiment described above. The communication device 1230 in RRCJNACTIVE initiates measurements for the SCG e.g. the PSCell, that it has stored as part of the UE Inactive AS Context when the communication device 1230 determines that it has UL data available for the SCG, such as UL data available for an SCG DRB or a sufficient amount of data available for a split DRB to justify SCG activation.

The method will be described in detail with reference to Figure 17, where the main actions or steps performed by the communication device 1230 according to a second embodiment is illustrated. The method comprises the following actions which action may be performed in any suitable order.

Action 1710

The communication device 1230 determines that uplink data becomes available. The communication device 1230 is in a suspended state, such as the RRCJNACTIVE state, and has MR-DC configured with an MCG and an SCG and that uplink data becomes available.

Action 1720

Action 1730

If the UL data is for an SCG DRB, the communication device 1230 initiates measurements for the SCG.

Action 1740

If the UL data is for a split DRB, the communication device 1230 further determines whether the amount of the UL data exceeds a threshold. The communication device 1230 initiates measurements for the SCG if the amount of data exceeds a network configured threshold value.

In one alternative the communication device 1230 performs continuous measurements on the suspended SCG e.g. the PSCell while it is in RRCJNACTIVE state. In one example, the communication device 1230 performs the measurements on the suspended SCG (PSCell), i.e. the one stored in the UE Inactive AS Context, while in RRCJNACTIVE state based on a network configuration. The network configuration may then e.g. be provided through system information, whereby it e.g. is valid in the cell where the configuration is broadcasted, or through dedicated signaling, such as e.g. in the RRC Release message that suspended the communication device 1230 to RRCJNACTIVE state.

In another alternative the communication device 1230 in RRCJNACTIVE state initiates measurements for the suspended SCG e.g. the PSCell that it has stored as part of the UE Inactive AS Context, when it determines that it has an amount of UL data available for a split DRB, which is above a threshold. The threshold can then be configured by the network, e.g. in system information or in dedicated signaling, e.g. the RRC Release message that suspended the communication device 1230 to RRCJNACTIVE state. In one example, the threshold value for initiating the measurements on the suspended SCG/PSCell is then lower than the threshold for indicating that the SCG should be activated and/or resumed.

In some alternatives of the above embodiments, the communication device 1230 indicates to the network node whether it is in coverage of the suspended SCG e.g. the PSCell as part of, or following, the RRC Resume procedure. The communication device 1230 may then e.g. indicate to the network node whether it is in coverage of the suspended SCG/PSCell through an SCG in-coverage indication. In one example, the communication device 1230 determines that it is in coverage of the suspended SCG e.g. the PSCell based on one or more threshold values, e.g. that the measured Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ) and/or Signal to Interference plus Noise Ratio (SINR) values for the suspended PSCell is/are above configured threshold value(s). The threshold values to determine whether the communication device 1230 is in coverage of the suspended SCG e.g. the PSCell may e.g. be based on a network configuration, which may be provided by the network node 1211 ,1212 to the communication device 1230 e.g. through system information or dedicated signaling, such as e.g. in the RRC Release message that suspended the communication device 1230 to RRCJNACTIVE state.

In one alternative, the UE transmits the measurement results for the SCG e.g. PSCell that was stored as part of the UE Inactive AS Context while the communication device 1230 was in RRCJNACTIVE state, e.g. measured RSRP, RSRQ and/or SINR values, in or following the RRC Resume procedure.

In some alternatives the indication whether the UE is in coverage of the suspended SCG/PSCell, i.e. the SCG in-coverage indication, and/or the measurement results for the suspended SCG/PSCell is/are provided by the communication device 1230 to the network node together with the UL data indication according to the above embodiments. In some alternatives, the SCG in-coverage indication and/or the measurement results for the suspended SCG/PSCell is/are provided by the communication device 1230 to the network node according to those methods even if no UL data indication is provided to the network node. In one example, the SCG incoverage indication and/or the measurement results for the suspended SCG/PSCell is/are provided within or multiplexed with an RRC Resume Request message, e.g. as one or more separate field(s) or using specific resume cause values. In another example, the SCG in-coverage indication and/or the measurement results for the suspended SCG/PSCell is/are provided within the RRC Resume Complete message or in another RRC message that is sent as part of, or after, the RRC Resume procedure, e.g. an UEAssistancelnformation message.

According to embodiments herein a method performed by the network node 1211 , 1212 is provided for handling a resume procedure for a communication device 1230 in the wireless communication network 1200.

According to a first embodiment, the network node 1211 , 1212 operates as a target network node e.g. a gNodeB where the communication device 1230 is attempting to resume. The method comprises receiving from the communication device 1230 an UL data indication, as described above e.g. associated to a suspended SCG, and based on that information, determining the SCG configuration for the communication device 1230, sometimes referred to as the MR-DC strategy to be set for the incoming communication device 1230.

The method will be described in detail with reference to Figure 18, where the main actions or steps performed by the network node according to the first embodiment is illustrated. The method comprises the following actions which action may be performed in any suitable order.

Action 1810

The network node 1211 , 1212 receives an UL data indication from the communication device 1230 during a resume procedure initiated by the communication device 1230.

Action 1820

The network node 1211 , 1212 determines a SCG configuration for the communication device 1230 based on the received UL data indication.

Action 1830

The network node 1211 , 1212 configures the communication device 1230 according the determined SCG configuration. This configuration may be provided in a message sent to the communication device 1230, for example in a RRCResume message as response to RRCResumeRequest or in a separate RRCReconfiguration message.

As part of the determination of the SCG configuration for the communication device 1230, the network node 1211 , 1212 performs at least one of the following actions:

Determining whether a suspend SCG is to be resumed and, if it is to be resumed, which mode of operation should be set to the SCG e.g. deactivated or activated;

Determining whether an SCG is to be released in case the UE trying to resume is configured with an SCG;

Determining whether an SCG is to be added in case the UE trying to resume is not configured with an SCG, and, if it is to be added, which mode of operation should be set to the SCG e.g. deactivated or activated.

According to embodiments herein, the method comprises the network node determining the MR-DC strategy based on the UL data indication and possibly other information such as the resource availability e.g. for the SCG, possibly indicated by the SN, or measurement results from the communication device 1230, e.g. RSRP, RSRQ, SINR from the communication device 1230 for the PSCell(s) and/or SCells of the SCG, which could have been obtained as an early measurement report.

According to a second embodiment, the network node 1211 , 1212, operating as a target network node e.g. a gNodeB where the UE is attempting to resume, receives an indication, as part of the RRC Resume procedure, from the communication device 1230 that it is in coverage of the SCG/PSCell that is stored as part of the UE Inactive AS Context, e.g. an SCG in-coverage indication. Based on this indication the network node 1211 , 1212 may determine whether to restore the suspended SCG e.g. PSCell or not. The indication may also be used by the network node 1211 , 1212 to determine whether to resume the SCG/PSCell in SCG activated state or SCG deactivated state. As an example, if the SCG in-coverage indication indicates that the communication device 1230 is not in coverage of the SCG e.g. the PSCell, the network node 1211 , 1222 does not resume the SCG, or it resumes the SCG in deactivated state, i.e. in an SCG power saving mode.

The network node 1211 , 1212 may also receive a measurement report from the communication device 1230 and use the content of that report in the determination of the SCG configuration. The method will be described in detail with reference to Figure 19, where the mam actions or steps performed by the network node according to the second embodiment is illustrated. The method comprises the following actions which action may be performed in any suitable order.

Action 1910

The network node 1211 , 1212 receives an SCG coverage indication from the communication device 1230 during a resume procedure initiated by the communication device 1230.

Action 1920

The network node 1211 , 1212 determines an SCG configuration for the communication device 1230 based on the received SCG coverage indication.

Action 1930

The network node 1211 , 1212 configures the communication device 1230 according to the determined SCG configuration. This configuration may be provided in a message sent to the communication device 1230, for example in a RRCResume message as response to RRCResumeRequest or in a separate RRCReconfiguration message.

To perform the method in the network node 1211 , 1212, the network node 1211, 1212 comprises modules as shown in Figure 20. The network node 1211, 1212 comprises a receiving module 2010, a transmitting module 2020, a determining module 2030, a processing module 2040, a memory 2050 etc.

The network node 1211 , 1212 is configured to perform any one of the Actions 1810- 1830, 1910-1930 described above.

The method according to embodiments herein may be implemented through one or more processors, such as the processor 2060 in the network node 1211 , 1212 together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of computer readable medium or a data carrier 2080 carrying computer program code 2070, as shown in Figure 11 , for performing the embodiments herein when being loaded into the network node 1211 , 1212. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server or a cloud and downloaded to the network node 1211 , 1212. Figure 21 shows an example embodiment for the communication device 1230 in which a method for handling a resume procedure may be implemented. The communication device 1230 comprises modules as shown in Figure 21. The communication device 1230 comprises a receiving module 2110, a transmitting module 2120, a determining module 2130, a processing module 2140, a memory 2150 etc. The communication device 1230 is configured to perform any one of the method Actions 1310-1350, 1710-1740 described above.

The method according to embodiments herein may be implemented through one or more processors, such as the processor 2160 in the UE 1230 together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of computer readable medium or a data carrier 2180 carrying computer program code 2170, as shown in Figure 21 , for performing the embodiments herein when being loaded into the UE 1230. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server or a cloud and downloaded to the communication device 1230.

Some example embodiments are listed in the following:

Embodiment 1 : A method performed by a communication device 1230, operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) of a network node 1211 , 1212 in a wireless communication network 1200, for handling a resume procedure from a first state, e.g. a suspended state to a second state, e.g. a connected state, wherein the network node 1211 , 1212 is a target network node that the communication device 1230 is to resume a connection, the method comprising:

Initiating a resume procedure;

Transmitting an uplink (UL) data indication to the network node 1211, 1212.

Embodiment 2: The method according to embodiment 1 , wherein the UL data indication indicates whether the resume is initiated due to uplink data that is available for the MCG, or for the SCG.

Embodiment s: The method according to any embodiments 1-2, further comprising determining type of data radio bearer for the UL data, such as whether the UL data is available for an MCG bearer, an SCG bearer or a split bearer. Embodiment 4: The method according to any embodiments 1-3, further comprising setting the UL data indication based on the type of the UL data.

Embodiment 5: The method according to any embodiments 1-4, wherein the UL data indication is one of a resume cause, a selection of PRACH resource such as a preamble, an assistance information message or an information element in the RRC Resume Complete message.

Embodiment 6: The method according to any embodiments 1-4, wherein the UL data indication is a value representing the amount of available data volume for the MCG or SCG.

Embodiment 7: A method performed by a communication device 1230 operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) of a network node 1211 , 1212 in a wireless communication network 1200, to perform measurements on the SCG, wherein the communication device 1230 is in a suspended state, the method comprising:

Determining that UL data becomes available; and

Performing measurements for the SCG.

Embodiment 8: The method according to embodiment 7, further comprising determining the type of the UL data, i.e. whether the UL data is available for an MCG bearer, an SCG bearer or a split bearer.

Embodiment 9: The method according to any embodiments 7-8, wherein performing measurements is based on the type of the UL data.

Embodiment 10: The method according to any embodiments 7-9, wherein performing measurements comprises one of initiating measurements, continuing measurements or stopping measurements.

Embodiment 11 : The method according to any embodiments 7-10, further comprising transmitting an SCG coverage indication to the network node.

Embodiment 12: The method according to embodiments 11 , wherein transmitting the SCG coverage indication is performed upon resuming from the suspended state.

Embodiment 13: The method according to any embodiments 7-10, further comprising transmitting a measurement report to the network node.

Embodiment 14: A method performed by a network node 1211 , 1212 for handling a resume procedure for a communication device 1230, wherein the communication device 1230 is operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) of the network node and is to request a resume from a first state, e.g. a suspended state to a second state, e.g. a connected state, the method comprising:

Receiving a request to resume from the communication device 1230;

Receiving an UL data indication from the communication device 1230;

Determining a SCG configuration of the communication device 1230 based on the UL data indication;

Configuring the communication device 1230 according to the determined SCG configuration.

Embodiment 15: A method performed by a network node 1211 , 1212 for handling a resume procedure for a communication device 1230, wherein the communication device 1230 is operating in dual connectivity with a master cell group (MCG) and a secondary cell group (SCG) of the network node and is to request a resume from a first state, e.g. a suspended state to a second state, e.g. a connected state, the method comprising:

Receiving a request to resume from the communication device 1230;

Receiving an SCG coverage indication from the communication device 1230;

Determining a SCG configuration of the communication device 1230;

Embodiment 16: The method according to embodiment 15, wherein determining a SCG configuration of the communication device 1230 is based on the SCG coverage indication.

Embodiment 17: The method according to embodiment 15, further comprising receiving a measurement report from the communication device 1230 and wherein determining the SCG configuration is based on the measurement report.

Embodiment 18: The method according to any embodiments 14-17, wherein determining a SCG configuration of the communication device 1230 comprises any one of:

- Determining whether a suspend SCG is to be resumed and, if it is to be resumed, which mode of operation should be set to the SCG e.g. deactivated or activated;

- Determining whether an SCG is to be released in case the communication device 1230 trying to resume is configured with an SCG;

- Determining whether an SCG is to be added in case the communication device 1230 trying to resume is not configured with an SCG, and, if it is to be added, which mode of operation should be set to the SCG e.g. deactivated or activated.

Claims

1. A method performed in a communication device (1230) for handling a resume procedure from a power saving mode of operation to a connected mode of operation, wherein the communication device (1230) is configured with multi-radio connectivity, MR-DC, with a first cell group and a second cell group in a wireless communication network (1200), the method comprising: initiating (1310) a resume procedure when there is an uplink, UL, data, available at the communication device (1230) while it is in the power saving mode of operation; determining (1320) whether a type of the UL data is for a first cell group bearer, a second cell group bearer or a split bearer; setting (1330) an UL data indication based on the type of UL data; and transmitting (1350) the UL data indication to a network node (1211 , 1212).

2. The method according to claim 1 , further comprising determining (1340) if the amount of the UL data exceeds a data volume threshold when the type of the UL data is for a second cell group bearer or a split bearer.

3. The method according to any one of claims 1-2, wherein the UL data indication is included in a resume request message and/or multiplexed with a resume request message to be transmitted to the network node (1211 , 1212).

4. The method according to any one of claims 1-3, wherein the UL data indication is transmitted or indicated as any one of the following: a) a resume cause comprised in a resume request message; b) a preamble associated to a preamble group and/or a specific timefrequency resource configured by the network node for the communication device (1230) to use for UL data indication; c) data mapped to a second cell group bearer to be transmitted by the second cell group; d) a selection of preamble(s) and/or specific time-frequency resource(s) configured by the network node for the communication device (1230) to use for different UL data indications; e) an assistance information message; f) an assistance information message multiplexed with a resume request message; g) a resume complete message transmitted after the communication device (1230) transmits the resume complete message; h) an information element in a resume complete message; i) a selection of Physical Random Access Channel, PRACH, resources configured by the network node for the communication device (1230) to use for UL data indication. The method according to any one of claims 1-4, wherein the UL data indication is a binary with two values representing whether the resume request is initiated due to that the UL data is available for the first cell group bearer or second cell group bearer, or whether the resume request is initiated due to that the UL data is available for the second cell group bearer or the amount of the UL data exceeds a data volume threshold for the split bearer. The method according to any one of claims 1-5, wherein the UL data indication further includes a data volume value representing the amount of UL data that is available for the first cell group bearer or a set of first cell group bearers, or for the second cell group bearer or a set of second cell group bearers, or for the split bearer or a set of split bearers. The method according to claim 6, wherein the data volume value for the split bearer or a set of split bearers is signaled to the network node separately from the two data volume values for the first cell group and second cell group bearers, or the data volume value for the split bearer or a set of split bearers is added to the data volume values for the first cell group and second cell group bearers, and only the data volume values for the first cell group and second cell group bearers are signaled to the network node (1211 , 1212). A method performed in a communication device (1230) for handling a resume procedure from a power saving mode of operation to a connected mode of operation, wherein the communication device is configured with multi-radio connectivity, MR-DC, with a first cell group and a second cell group in a wireless communication network (1200), the method comprising: determining (1710) whether there is an uplink, UL, data available at the communication device (1230) while it is in the power saving mode of operation; determining (1720) whether a type of the UL data is for a first cell group, a second cell group or a split bearer; initiating (1730) measurements for the second cell group if the type of the UL data is for the second cell group bearer, or if the type of the UL data is for the split bearer and the amount of UL data exceeds a threshold value configured by the network node (1211 , 1222). The method according to claim 8, further comprising transmitting an indication to the network node (1211 , 1211) for indicating whether the communication device (1230) is in a coverage of the second cell group as part of or following the resume procedure from the power saving mode of operation to the connected mode of operation. The method according to claim 9, further comprising determining whether the communication device (1230) is in the coverage of the second cell group based on whether any one or more measured values on Reference Signal Received Power, RSRP, Reference Signal Received Quality, RSRQ, Signal to Interference plus Noise Ratio, SINR, for the second cell group is or are above one or more threshold value(s). The method according to claim 8, further comprising transmitting measurement results for the second cell group to the network node (1211 , 1211) in or following the resume procedure from the power saving mode of operation to the connected mode of operation. The method according to claims 9 and 11 , wherein the indication of whether the communication device (1230) is in a coverage of the second cell group and/or the measurement results for the second cell group is/are transmitted to the network node (1211 , 1211) together with an UL data indication. The method according to claims 9 and 11 , wherein the indication of whether the communication device (1230) is in a coverage of the second cell group and/or the measurement results for the second cell group is/are transmitted within or multiplexed with a resume request message as one or more separate field(s) or using specific resume cause values. The method according to claims 9 and 11 , wherein the indication of whether the communication device (1230) is in a coverage of the second cell group and/or the measurement results for the second cell group is/are transmitted within a resume complete message or in an assistance information message that is sent as part of, or after the resume procedure. A communication device (1230) configured to perform the method according to any one of claims 1-14. A method performed in a network node (1211 , 1212) for handling a resume procedure for a communication device (1230) from a power saving mode of operation to a connected mode of operation in a wireless communication network (1200), wherein the communication device is configured with multi-radio connectivity, MR-DC, with a first cell group and a second cell group, the method comprising: receiving (1810, 1910) an uplink, UL, data indication or a second cell group coverage indication indicating whether the communication device (1230) is in a coverage of the second cell group from the communication device (1230) during a resume procedure initiated by the communication device (1230), wherein the UL data indication indicating a type of the UL data whether it is for a first cell group, a second cell group or a split bearer; determining (1820, 1920) a second cell group configuration for the communication device (1230) based on the received UL data indication or second cell group coverage indication; and configuring (1830, 1930) the communication device (1230) according the determined second cell group configuration. The method according to claim 16, wherein configuring (1830, 1930) the communication device (1230) is performed by transmitting the determined second cell group configuration in a resume message or in a separate reconfiguration message to the communication device (1230). The method according to any one of claims 16-17, wherein determining (1820) a second cell group configuration for the communication device (1230) based on the received UL data indication comprises one or more of the following actions: a) determining whether a suspended second cell group is to be resumed, and if it is determined that the suspended second cell group is to be resumed, setting a mode of operation to the second cell group with deactivated or activated; b) determining whether an second cell group is to be released in case the communication device (1230) is attempting to resume is configured with a second cell group; c) determining whether an SCG is to be added in case the communication device (1230) is attempting to resume is not configured with a second cell group, and, if it is determined that a second cell group is to be added, setting a mode of operation to the second cell group with deactivated or activated. The method according to any one of claims 16-18, further comprises configuring, by system information or a dedicated signaling, any one or a combination of the following: a) a preamble or a group of preamble(s), b) one or a set of specific time-frequency resource(s), c) a data volume threshold, d) a set of Physical Random Access Channel, PRACH, resources, for the communication device (1230) to use for different UL data indications. The method according to claim 16, wherein receiving (1810, 1910) an uplink, UL, data indication or a second cell group coverage indication comprises any one of: a) receiving an UL data indication or second cell group coverage indication in a resume request message sent by the communication device (1230), wherein the UL data indication is a parameter comprised in the resume request message; b) receiving an UL data indication as a resume cause, wherein a new resume cause is set to indicate that the resume procedure has been triggered due to a certain amount of data mapped to a second cell group bearer or split bearer being above a data volume threshold, or a new resume cause is set to indicate that the communication device (1230) has an amount of UL data in buffer above a data volume threshold regardless of that being associated to second cell group bearers, or when the UL data is for a second cell group bearer, an existing resume cause is set to a value "mo-data" or to another existing resume cause; c) receiving an UL data indication in an assistance information message or in an assistance information message multiplexed with a resume request message, or in a resume complete message, or in an information element in a resume complete message; e) receiving an UL data indication in a preamble or a group of preamble(s), or in one or a set of specific time-frequency resource(s) or Physical Random Access Channel, PRACH, resource(s), wherein the preambles, the specific time-frequency resource(s) or PRACH resources are configured to indicate different UL data indications. A network node (1211 , 1212) configured to perform the method according to any one of claims 16-20.