Patent Application
20240188159
Embodiments herein relate to network nodes and methods therein. In particular, they relate to handling operation mode 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.
In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) 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 Wi-Fi 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.
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
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
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:
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:
For EN-DC and NR-DC, the major changes compared to LTE DC are:
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
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. In RAN-2 108, further discussion was made to clarify the further studies (FFSs). Some solutions have been proposed in Rel-16, but these have different problems.
RAN2#113bis-e has the following agreements for the Deactivation of SCG.
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.
As part of developing embodiments herein problems were identified and will first be discussed.
The change of SCG mode of operation can either be initiated by the SN, i.e. SN-initiated, or by the MN, i.e. MN-initiated.
SN-Initiated Change: MN can Reject and/or Accept
When the change for SCG mode of operation is initiated by the SN, the MN may need to decide whether the request is accepted or rejected. However, especially in the case the request is rejected, the SN would not be aware of the reason for the rejection. One issue is that relevant input to the SCG activation/deactivation decision for rejecting an SN-initiated request at the MN may come from the UE. This may be for instance information that the UE overheating or that UE is low on battery. This information is typically transmitted to the MN, as part of UE assistance information procedure, and is not available to the SN. Not knowing the rejection could prevent the SN to take follow up actions e.g. decide to release the SCG and/or to wait some time before it can send another request. For example, let us assume the SCG is deactivated. And, the MN becomes aware, e.g. via UE assistance, that UE is overheating. If SN requests the activation of the SCG, the MN rejects the request from the SN to activate the SCG, but the SN would not be aware of the reason.
MN-Initiated Change: SN can Reject and/or Accept
When the change for SCG mode of operation is initiated by the MN e.g. due to some internal algorithm at the MN, this time is the SN that may need to decide whether the request is accepted or rejected. However, especially in the case the request is rejected, the MN would not be aware of the reason for the rejection, which might be something internal at the SN and/or related to the SCG configuration. One issue is that relevant input to the SCG activation/deactivation decision for rejecting an MN-initiated request at the SN may come from the UE via SRB3 e.g. UE Assistance Information via SRB3. This may be for instance information that the UE overheating or that UE is low on battery. If over SRB3, this information is transmitted to the SN, as part of UE assistance information procedure, and is not available to the MN. Not knowing the rejection could prevent the MN to take follow up actions e.g. decide to release the SCG and/or to wait some time before it can send another request.
Therefore, it is an object of embodiments herein to provide an improved method for handling SCG operation mode change in a wireless communication network.
According to one aspect of the embodiments herein, the object is achieved by a first network node e.g. MN and method therein for handling SCG mode of operation by providing a rejection reason to a second network node e.g. the SN. The rejection reason may be, e.g. a cause value, to reject a request for change of an SCG mode for a UE. The first network node may transmit information enabling the second network node to determine an SCG mode of operation e.g. an ACTIVITY NOTIFICATION message to the second network node.
The first network node receives a request from the second network node for change of mode of operation of the SCG.
The first network node transmits a response to the second network node, where the change of the SCG mode of operation is accepted or rejected.
If the change of the SCG mode of operation is rejected, the response including an indication of a specific reason for rejection.
If the change of the SCG mode of operation is accepted, the first network node transmits to the communication device a message including a reconfiguration or command to change the SCG operation mode.
According to one aspect of the embodiments herein, the object is achieved by a second network node e.g. SN and method therein for handling SCG mode of operation by requesting a change of SCG operation mode to a first network node e.g. MN.
The second network node may receive information enabling the second network node to determine the SCG mode of operation e.g. an ACTIVITY NOTIFICATION message received by the second network node.
The second network node transmits a request to the first network node for change of SCG operation mode.
The second network node receives a response from the first network node, where the change of the SCG operation mode may be accepted or rejected by the first network node.
If the change of the SCG operation mode is rejected, the response from the first network node including an indication of a reason for rejection.
According to some embodiments herein, the first network node may be operating as a Master Node (MN) for a UE configured with MR-DC with a master cell group (MCG) and a secondary cell group (SCG). The request for change of SCG operation mode may be an SN-initiated request that may be rejected by the MN.
According to some embodiments herein, the second network node may be operating as a Secondary Node (SN) for a UE configured with MR-DC. The request for change of SCG operation mode may be an SN-initiated request that may be rejected by the MN.
According to some embodiments herein, the first network node may be operating as a Secondary Node (SN) for a UE configured with MR-DC. The request for change of SCG operation mode may be an MN-initiated request that may be rejected by the SN.
According to some embodiments herein, the second network node may be operating as a Master Node (MN) for a UE configured with MR-DC. The request for change of SCG operation mode may be an MN-initiated request that can be rejected by the SN.
In other words, according to the embodiments herein, the MN informs the SN of the detailed reason when rejects the request on SCG (de)activation. The SN informs the MN of the detailed reason when rejects the request on SCG (de)activation.
Advantages of embodiments herein are:
To help the SN to understand the reason for rejection of SCG (de)activation, and be well prepared for its own resource allocation.
To enable the SN to take further actions depending on the exact cause value e.g. release the SCG resources etc.
Similar benefits exist for the MN case.
The reject reason is important for the SN to take decision on possible further actions, e.g. whether or when to request the change for SCG mode of operation again and/or to release the SCG and/or to change the PSCell. For instance, if the reason for the reject of SCG activation is UE overheating, then the SN should wait before sending the activation request again. On the other hand, if the reason for reject of SCG deactivation is that MN expects more data, then SN can resend the deactivation request once the data is transmitted.
Therefor embodiments herein provide an improved method for handling SCG mode of operation 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.
Examples of embodiments herein are described in more detail with reference to attached drawings in which:
Embodiments herein relate to communications networks in general.
In the wireless communication network 800, one or more wireless communication devices 830, 831 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 800 such as a first network node 811 and a second network node 812. The first and second network node 811, 812 may be any of RAN node, such as gNB, eNB, en-gNB, ng-eNB, gNB etc. The first network node 811 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 812 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 OAM node.
The first and second network nodes 811 and 812 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 811 and 812 depending e.g. on the radio access technology and terminology used. The first and second network nodes 811 and 812 may be referred to as a source and target network node, respectively, and may communicate with the wireless communication device 830, 831 with Downlink (DL) transmissions to the wireless communication device 830, 831 and Uplink (UL) transmissions from the wireless communication device 830, 831.
The first and second network nodes 1211, 1212 may each be either a master node (MN) having a master cell group MCG, or a secondary node (SN) having a secondary cell group SCG, respectively, as shown in
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:
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 first network node 811, e.g. a MN or a SN is provided for handling SCG operation mode change in the wireless communication network 800. The method will be described in detail with reference to
This action is optional. The MN, i.e. the first network node 811, may receive a UE Assistance Information message from a UE, e.g. the first communication device 830. This message contains information that the UE wants to relay to the network node for information about the UE status. This message may contain assistance information about e.g. UE overheating, UE power saving. Information related to UE power saving may be max aggregated bandwidth, max number of component carriers, max number of MIMO layers, etc.
This action is optional. The first network node 811 may transmit an ACTIVITY NOTIFICATION message to a SN, e.g. the second network node 812. This message contains information that there is user plane traffic on a certain session or that there is absence of user plane traffic on a certain session.
The first network node 811 receives a request from the second network node 812 e.g., SN or MN, for change of mode of operation of the SCG.
The request may be S-NODE MODIFICATION REQUIRED with a request of activated or deactivated SCG.
The request may be S-NODE MODIFICATION REQUEST with a request of activated or deactivated SCG.
In other words, the request includes an indication of the change of mode of operation for the SCG that the second network node 812 proposes e.g. deactivate or activate SCG.
According to some embodiments herein, the second network node 812 may request the first network node 811 to change an SCG in deactivated mode to activated mode of operation.
According to some embodiments herein, the second network node 812 may request the first network node 811 to change an SCG in activated mode to deactivated mode of operation.
The first network node 811 determines based on e.g. received UE assistance information or current UE traffic situation, etc. whether to accept or reject the request for change in the SCG mode of operation.
If the change in SCG configuration and/or change of SCG mode of operation is accepted, the first network node 811 transmits to the UE a message including a reconfiguration or command to change the SCG configuration and/or mode of operation of the SCG.
The first network node 811 receives response from the UE, e.g. an RRC Reconfiguration Complete message.
If the changes in SCG configuration and SCG mode of operation are not accepted, the above Actions 915 and 916 will not be performed, the first network node 811 performs instead the following actions. If the change in SCG configuration is accepted, but not the change in the SCG mode of operation, the first network node 811 performs the above Actions 915 and 916 and further performs the following actions.
The first network node 811 transmits a response to the second network node 812 e.g., SN or MN, where the change of the SCG mode is accepted or rejected.
In one alternative, the first network node 811 does not accept the requested change of SCG mode of operation, but may accept other changes to the SCG configuration. In this case, the rejection of requested mode of operation may be indicated by the first network node 811 transmitting an acknowledge message, e.g. S-NODE MODIFICATION CONFIRM or S-NODE MODIFICATION REQUEST ACKNOWLEDGE including an indication that the change of SCG mode of operation is rejected and the reason for the rejection, e.g., UE overheating, UE power saving preference, expected new data, etc.
In another alternative, the first network node 811 does not accept the requested change of SCG mode of operation nor any other change to the SCG configuration. In this case, the rejection is indicated by the first network node 811 transmitting an S-NODE MODIFICATION REFUSE or S-NODE MODIFICATION REQUEST REJECT message. Possibly this may be indicated by a new cause value or multiple cause values in the message, e.g., UE overheating, UE power saving preference, expected new data, etc. In addition, this could indicate that the reason for not accepting the SCG configuration was due to not accepting a change of mode of operation i.e. that may indicate that if the second network node 812 sends another S-NODE MODIFICATION REQUIRED or S-NODE MODIFICATION REQUEST with a different SCG mode of operation that could be accepted.
Further examples of cause values at rejection of an activation may be e.g. lack of resources, UE out of coverage of the PSCell/SCG, etc. Further examples of cause values at rejection of an deactivation may be e.g. the network node does not expect much data and is soon releasing and/or inactivating/suspending the UE that may include an indication to release resources and/or suspend the resources etc.
According to embodiments herein a method performed by a second network node 812, e.g. a MN or a SN is provided for handling SCG operation mode change in the wireless communication network 800. The method will be described in detail with reference to
This action is optional. The second network node 812 may receive an ACTIVITY NOTIFICATION message from the first network node 811. The second network node 812 may determine to change the mode of operation of the Secondary cell group (SCG) configuration e.g. based on a received ACTIVITY NOTIFICATION, based on measurement reports received from the UE and/or further input like traffic demands, e.g. deactivated to activated or activated to deactivated.
The second network node 812 transmits a request e.g. an SN Modification Request to a first network node 811 for a change of SCG mode of operation, from activated to deactivated or from deactivated to activated.
The second network node 812 receives a response from the first network node 811 where the modification of the mode of operation of the SCG may be accepted or rejected.
In one alternative, the second network node 812 may receive a response from the first network node 811 where the modification of the mode of operation of the SCG is rejected while other modifications of the SCG may be accepted. The rejection reason of the change of the operation mode is indicated in an acknowledge message, e.g. S-NODE MODIFICATION CONFIRM or S-NODE MODIFICATION REQUEST ACKNOWLEDGE including an indication that the change of SCG mode of operation is rejected and the reason for the rejection, e.g., UE overheating, UE power saving preference, expected new data, and etc.
In another alternative, the second network node 812 may receive a response from the first network node 811 where the modification of the mode of operation of the SCG is rejected. The rejection may be indicated in S-NODE MODIFICATION REFUSE or S-NODE MODIFICATION REQUEST REJECT, possibly together with a new cause value or multiple cause values, e.g., UE overheating, UE power saving preference, expected new data, etc.
Further examples of cause values at rejection of an activation may be e.g. lack of resources, UE out of coverage of the PSCell/SCG, or other. Further examples of cause values at rejection of an deactivation may be e.g. the network node does not expect much data and is soon releasing and/or inactivating/suspending the UE, that may include an indication to release resources and/or suspend the resources.
The methods described above with respect to the first and second network node 811, 812 for handling SCG operation mode change is assumed that the SCG activation/deactivation is initiated by a SN. However the methods described above may equally apply to the situation where the SCG activation/deactivation is initiated by a MN.
According to embodiments herein a method performed by a communication device 830 is provided for handling SCG operation mode change in the wireless communication network 800. The communication device 830 sends UE assistance information to the MN. The communication device 830 receives a reconfiguration or command from an MN for change SCG configuration and/or change of SCG mode of operation, e.g. change from activated to deactivated or from deactivated to activated and sends a response to the MN e.g. an RRC Reconfiguration Complete message etc.
To perform the method in the first/second network node 811/812, the first/second network node 811/812 comprises modules as shown in
The first/second network node 811/812 is configured to perform any one of the Actions 911-917, 1010-1030 described above.
The method according to embodiments herein may be implemented through one or more processors, such as the processor 1260 in the network node 811/812 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 1280 carrying computer program code 1270, as shown in
Some example embodiments are listed in the following:
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2022/050437 | 5/5/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63184914 | May 2021 | US |
