Patent Description:
Multi-RAT Dual Connectivity (MR-DC) refers to a range of different DC configuration options available in a User Equipment (UE) and is largely associated with <NUM>th Generation (<NUM>) cellular mobile communication standards. In the MR-DC, a Master RAN Node (MN) functions as a controlling entity, and utilizes a Secondary RAN Node (SN) for additional data capacity. Examples of MR-DC configurations for the UE include EN-DC (E-UTRA - NR Dual Connectivity) configuration, NR-NR-DC (New Radio-New Radio Dual Connectivity) configuration, NGEN-DC (NG-RAN - E-UTRA Dual Connectivity) configuration, NE-DC (NR - E-UTRA Dual Connectivity) configuration and the like. MR-DC is described as in REL-<NUM>3GPP standards (TS <NUM>), where multiple transmitters and receivers (Tx/Rx) at the UE may be configured to utilize radio resources of both NR (New Radio) and EUTRA (Evolved-Universal Terrestrial Radio Access-New Radio) in an ENDC configuration. The UE is connected to eNB (evolved node B) that acts as MN and one gNB (<NUM>th Generation node B) that acts as SN. The UE indicates this capability to operate on the MR-DC using UE capability information message to a network node.

Despite the benefits of the MR-DC capability of the UE, it is desirable to disable (or enable) the MR-DC capability dynamically of the UE in certain scenarios, like low battery or high temperature triggers in order to mitigate their effects. The UE has to indicate the networks of its MR-DC capability. <NPL>), discusses the necessity and methods to support UE overheating in EN-DC. <CIT> relates to user equipment (UE) radio capability handling in LTE (long term evolution). <NPL>), discusses UE capability temporary restrictions. <NPL>), discusses use cases for UE requested configuration change. <NPL>), discusses the UEAssistancelnformation message into which a change request is added. "<NPL>), discloses providing power preference indications from a UE to the network and the network acts based on the indications.

As defined in 3GPP specifications, the existing system has limitations in realizing signaling overhead to disable/enable the MR-DC capability. Further, the system does not allow the UE capability change in EMM (EPS Mobility Management)-connected state.

The MR-DC capable UE encounters local trigger to deactivate NR modem to disable the MR-DC capability. In conventional method, the UE needs to initiate TAU (Tracking Area Update) procedure and send signaling messages to the RAN for updating the RANs about the deactivation of the NR Modem at the UE. The signaling messages includes RACH (Random access channel)procedures with EUTRAN (Evolved Universal Terrestrial Radio Access Network), security procedure between UE and EUTRAN, radio capability request procedures between MME (Mobile Management Entity) and EUTRAN, the UE capability update between UE and EUTRAN, the UE capability indication between EUTRAN and MME and TAU procedures among the UE, EUTRAN and MME. Thus a lot of signaling message exchanges has to be done among UE, MME and EUTRAN just to update the UE capability.

Thus, it is desired to address the above mentioned problems and at least provide a useful alternative for indicating the change in the dual capability of the UE.

The principal object of the embodiments herein is to provide a method and system for indication of a change in an MR-DC capability of the UE to the RANs and core network.

Another object of the embodiment herein is to hold a Tracking Area Update (TAU) message at the UE while updating the change in the MR-DC capability of the UE to the RANs and core network.

Another object of the embodiment herein is to identify detection of a particular event when the UE is in connected mode.

Another object of the embodiment herein is to identify configuration of UE-assistance information when the UE is in connected mode.

Another object of the embodiment herein is to regulate the indication of a change in the MR-DC capability of the UE to the network node.

Accordingly the invention is set out in the appended claims.

This disclosure is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:.

As is traditional in the field, embodiments may be described and illustrated in terms of blocks which carry out a described function or functions. These blocks, which may be referred to herein as managers, units, modules, hardware components or the like, are physically implemented by analog and/or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits and the like, and may optionally be driven by firmware and software. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like. The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block. Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure. Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

The embodiments herein disclose a method for indicating the change in the MR-DC capability of the UE to the network node. The method comprises detecting a change in the MR-DC capability of the UE and determining, whether the UE is in one of an idle mode and a connected mode. The method further comprises holding a tracking area update (TAU) message at the UE, if the UE is in the idle mode, and determining whether a particular event is detected, and regulating an indication of the change in the MR-DC capability of the UE to the network node based on the detection of the particular event. The particular event comprises at least one of an MO/MT request, a data request, a signalling request, and a SMS request, and wherein the particular event configures the UE into the connected mode. The method further comprises determining whether UE-assistance information is configured by the network node, when the UE is in connected mode and regulating an indication of the change in the MR-DC capability of the UE to the network node based on the configuration of the UE-assistance information with the network node.

Unlike conventional methods and systems, the proposed method reduces signaling overhead and ensures successful indication of the change in MR-DC capability of the UE to the network node. The proposed method also ensures indication of the change in MR-DC capability of the UE to the network node while in a connected mode. In conventional systems, the UE is first changes to idle mode and then the indication is sent to the network node.

<FIG> represents a system diagram of a UE <NUM> with an MR-DC capability. As seen in <FIG> the UE <NUM> is in connection with both an LTE (Long Term Evolution) eNB <NUM> and an NR (New Radio) gNB <NUM>. The eNB <NUM> is a master node (MN) and the gNB <NUM> is a secondary node (SN). The eNB <NUM> and the gNB <NUM> are connected to an S-GW <NUM> (Serving Gateway) which acts as a core network. The eNB <NUM> is also connected to an MME <NUM> (Mobile Management Entity) which is also a part of the core network. The MR-DC capability of the UE <NUM> needs to be changed dynamically that is the dual capability of the UE <NUM> may be enabled or disabled based on an occurrence of a local trigger event from the UE <NUM>. The local trigger event may be at least one of a low battery trigger, a high temperature trigger and the like. In order to mitigate the effect of the local trigger event it is necessary to deactivate the secondary RAT (secondary modem) (SN) <NUM> from the dual connectivity of the UE <NUM>. Thus the MR-DC capability of the UE <NUM> needs to be disabled. This change in the MR-DC capability of the UE <NUM> has to be indicated to the core network MME <NUM> and S-GW <NUM>.

In conventional method, in order to indicate the change in the MR-DC capability of the UE <NUM> to the core network S-GW <NUM> and MME <NUM>, a TAU procedure is initiated by the UE <NUM>. Signaling messages get exchanged between the UE <NUM>, eNB <NUM>, gNB <NUM> and the core network MME <NUM> and S-GW <NUM>, when the TAU procedure is initiated. The signaling messages includes RACH procedures between the UE <NUM>, the eNB <NUM> and the gNB <NUM>, security procedure between UE <NUM>, eNB <NUM>, and gNB <NUM> and radio capability request procedures between S-GW <NUM>, MME <NUM>, eNB <NUM> and the gNB <NUM>, the UE capability update between the UE <NUM>, the eNB <NUM>, and the gNB <NUM>, the UE capability indication between the enb <NUM>, the gnb <NUM>, the S-GW <NUM> and the MME <NUM> and TAU procedures between the UE <NUM>, the eNB <NUM>, the gNB <NUM>, the S-GW <NUM> and the MME <NUM>. A lot of signaling message exchanges has to be done, just to update the UE capability between the UE <NUM>, the MME <NUM>, the gNB <NUM> and the eNB <NUM>. There arises a problem of signaling overhead whenever the MR-DC capability of the UE <NUM> has to be enabled again. Further when the local trigger event is occurring frequently, the MR-DC capability of the UE <NUM> needs to be changed and thus for every change in the MR-DC capability, the TAU procedures, the security procedure and the other signaling has to be done. This results in ping pong effect. Further there may be an RACH procedure failure due to temporary network condition or signal conditions.

<FIG> depicts a sequence diagram illustrating the signaling procedure of updating the eNB <NUM> and the MME <NUM> of the change in the MR-DC capability of the UE <NUM> for the conventional method. The TAU procedure relates to a series of procedures performed by the UE <NUM> for updating the Tracking Area (TA). As seen in <FIG> the TAU procedure (<NUM>) is initiated between the UE <NUM> and the MME <NUM>. After initiating the TAU procedure (<NUM>), an RACH procedure (<NUM>) between the UE <NUM> and eNB <NUM> has to be exchanged. The signaling further includes exchanging a security procedure (<NUM>) between the UE <NUM> and eNB <NUM>. A radio capability request procedures (<NUM>) between the MME <NUM> and the eNB <NUM> is also exchanged. The UE capability update between the UE <NUM> and the eNB <NUM> and the UE capability indication between the eNB <NUM> and the MME <NUM> is also exchanged. The TAU procedures between the UE <NUM>, the eNB <NUM> and the MME <NUM> are also initiated. Thus a lot of signaling message exchanges need to happen just to update the UE capability between the UE <NUM>, the MME <NUM> and the eNB <NUM>. There arises a problem of signaling overhead whenever the UE <NUM> has to change the mode. Further when the local trigger is occurring frequently, the MR-DC capability of the UE <NUM> needs to be changes and thus for every change in the MR-DC capability, the TAU procedures, the security procedure and the other signaling has to be done. This results in ping pong effect. Further there may be an RACH procedure failure due to temporary network condition or signal conditions. Further when the UE <NUM> is in connected mode the prior arts/conventional system and method discloses changing the UE <NUM> to idle mode first and then updating the network about the changed MR-DC capability of the UE <NUM>. However, conventional systems and method does not state anything about updating the MR-DC capability while the UE <NUM> is in the connected mode. The proposed system and method provides a solution to the above said problems. The proposed system and method also provide the feature of updating the MR-DC capability while the UE <NUM> is in the connected mode.

<FIG> discloses a UE <NUM> for the proposed method for indicating the change in the MR-DC capability of the UE <NUM> to the MME <NUM> and the eNB <NUM>. The examples for the UE <NUM> are, but not limited to a smart phone, a tablet computer, a personal computer, a desktop computer, a mobile device, a personal digital assistance (PDA), a multimedia device, an Internet of Things (IoT) and the like. The UE <NUM> is an MR-DC capable UE. The UE <NUM> may comprise multiple transceivers Tx/Rx and is configured to utilize radio resources of both NR (New Radio) and EUTRA (Evolved-Universal Terrestrial Radio Access-New Radio). The UE <NUM> may be connected to one eNB that acts as an MN <NUM> (Master Node) and one gNB that acts as SN (secondary node) <NUM>. The MR-DC capability of the MR-DC capable UE <NUM> has to be enabled/disabled dynamically based on the occurrence of the local trigger. The change in the MR-DC capability of the UE <NUM> has to be indicated to the EUTRA <NUM> and the MME <NUM>. The UE <NUM> is in a connected mode or an idle mode with respect to the network. In the idle mode, the UE <NUM> has no signaling or data bearers associated with it. In other words, no network/radio resources are allocated to the UE <NUM>. In the connected mode, the UE is associated with the network/radio resources.

The UE <NUM> comprises a memory <NUM>, a processor <NUM>, and an MR-DC connectivity regulator <NUM>. The MR-DC connectivity regulator <NUM> comprises a TAU trigger <NUM>, an event detector <NUM> and a timer <NUM>. The MR-DC connectivity regulator <NUM> is configured to indicate the change in the MR-DC capability of the UE <NUM> to the MME <NUM> and the eNB <NUM>.

In an embodiment the MR-DC connectivity regulator <NUM> detects the change in the MR-DC capability of the UE <NUM>. The MR-DC connectivity regulator <NUM> is configured to determine whether the UE <NUM> is in one of the idle mode and the connected mode. If the UE <NUM> is in the idle mode then the TAU trigger <NUM> holds the TAU message at the UE <NUM>. The event detector <NUM> then determines whether an event is detected, and the MR-DC connectivity regulator <NUM> regulates an indication of the change in the MR-DC capability of the UE <NUM> to the MME <NUM> and the eNB <NUM> upon detection of the event. The event comprises at least one of a Mobile terminated/Mobile originated (MO/MT) request, a data request, a signaling request, and an SMS request, which configures the UE <NUM> into the connected mode. In an example the MO/MT trigger is a trigger by the UE <NUM> establishing the connection with the network either for mobile originated or mobile terminated cases.

If the UE <NUM> is in the connected mode the MR-DC connectivity regulator <NUM> determines whether UE-assistance information is configured by the network node. The TAU trigger <NUM> triggers the message indicating the change in the MR-DC capability of the UE <NUM> to the MME <NUM> and the EUTRA based on the configuration of the UE-assistance information with the network node.

In an embodiment, a secondary cell group (SCG) failure indication message is triggered by the MR-DC connectivity regulator <NUM>. The timer <NUM> is initiated to receive an acknowledgement of the SCG failure indication message. The MR-DC connectivity regulator <NUM> determines that the timer <NUM> is expired and the acknowledgement of the SCG failure indication message is not received or the acknowledgement of the SCG failure indication message is received before expiry of the timer <NUM>. The TAU trigger <NUM> triggers the message indicating the change in the MR-DC capability of the UE <NUM> to the EUTRA and the MME, in response to determining that the DC for the SN is configured.

<FIG> shows a flow diagram <NUM> for sending TAU messages to the EUTRA <NUM> and the MME <NUM> when the UE <NUM> is in an idle mode. As shown in <FIG>, at step <NUM> the local trigger is received. The MR-DC capability of the UE <NUM> is enabled/disabled based on the local trigger. At step <NUM>, the MR-DC connectivity regulator <NUM> determines whether the UE is in the idle mode or connected mode. The method proceeds to step <NUM> if the UE <NUM> is in the idle mode and to <NUM> if the UE <NUM> is in the connected mode. At step <NUM>, the TAU trigger <NUM> keeps the TAU message pending at the UE <NUM>. At step <NUM>, the MO/MT (mobile originated/mobile terminated) trigger is received. At step <NUM> after receiving the MO/MT trigger the TAU trigger <NUM> sends the TAU messages to the network indicating the change in the MR-DC capability of the UE <NUM>.

<FIG> and <FIG> disclose a sequence diagram of the flow <NUM> explaining the updating of the EUTRAN and the MME <NUM> of the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the idle mode. The sequence diagram shows the UE <NUM>, the EUTRA <NUM> and the MME <NUM>. The sequence diagram explains the process of indicating the MR-DC capability of the UE <NUM> to the network when the UE <NUM> is in the idle mode. As shown in the <FIG>, the trigger to disable the MR-DC is received, while the UE <NUM> is in the idle mode. The TAU messages are kept pending at the UE <NUM> by the TAU trigger <NUM> until the MO/MT trigger is received. As shown in <FIG>, the MO/MT trigger is received and the UE <NUM> checks if the trigger to disable the MR-DC capability of the UE still exists. If the trigger to disable the MR-DC capability of the UE <NUM> is valid then the UE <NUM> requests an RRC (Radio Resource Control) to send the TAU messages with radio capability update to the network. The RRC connection has to be established with the EUTRA <NUM> to send the MR-DC capability update of the UE <NUM> to the network. As shown in the <FIG>, an RACH procedure is followed. The RACH procedure refer to the first message from the UE <NUM> to the eNB <NUM>, when the UE <NUM> is powered and is used for uplink synchronization between the UE <NUM> and the eNB <NUM>. A Random Access Preamble (MSG1) is sent to the EUTRA <NUM>. A Random Access Response (MSG2) is received by the UE from the EUTRA <NUM>. An RRC Connection Request (MSG3) is sent to the EUTRA <NUM>. In response to the RRC connection request, an RRC Connection Setup (MSG4) is received by the UE <NUM>. The RRC connection is completed and the TAU message is encapsulated and the uplink information transfer is done as the message is sent to the EUTRA <NUM>. The EUTRA <NUM> sends the TAU messages to the MME <NUM>. The MME <NUM> receives a message for disabling the MR-DC capability of the UE <NUM> in its database. As shown in the <FIG>, the MME <NUM> sends an initial context setup request to the EUTRA <NUM>, and then the MME sends a UE MR-DC capability match request to the EUTRA <NUM>. The EUTRA <NUM> checks the UE <NUM> for the MR-DC capability of the update. Upon receiving the response from the UE <NUM> about the MR-DC capability information, the EUTRA <NUM> forwards the update in the MR-DC capability of the UE <NUM> to the MME <NUM>. The MME <NUM> disables the MR-DC capability of the UE <NUM> and sends downlink information to the EUTRA <NUM> indicating that the TAU message indicating the change in the MR-DC capability of the UE <NUM> is accepted. The EUTRA <NUM> sends the TAU accept message to the UE <NUM>. The UE then sends uplink information stating that the TAU procedure is complete to the EUTRA <NUM>. The EUTRA <NUM> then forwards it to the MME <NUM>.

<FIG> shows the time diagram for indicating the change in the MR-DC capability of the UE <NUM> when the UE 100is in the idle mode for conventional methods. <FIG> shows the time diagram for indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the idle mode for the proposed method. As can be seen in <FIG> there is an RACH failure, while updating the MR-DC capability of the UE <NUM>, whereas in <FIG> the RACH failure is avoided, as the TAU procedure is kept pending at the UE <NUM>.

<FIG> is a flow diagram <NUM> for indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. As shown in <FIG> the UE <NUM> is determined to be in the connected mode at step <NUM>. At step <NUM> it is determined whether UE-assistance information is configured to the network. In an embodiment the UE-assistance information comprises an Information Element (IE) indicating the change in the MR-DC capability of the UE (<NUM>).

In an example embodiment a UE-assistance information message is used for the indication to the eNB <NUM>. The UE-assistance information message may perform the following function but not limited to informing the eNB <NUM> about a power saving preference. Upon configuring the UE <NUM> to provide power preference indications, the eNB <NUM> may consider that the UE <NUM> does not prefer a configuration primarily optimised for power saving until the UE <NUM> explicitly indicates otherwise. For example, the UE-assistance information message is used but not limited to indicate the power preference of the UE to the network.

The method proceeds to step <NUM> if the UE assistance information is configured to the network and to step <NUM> if the UE-assistance information is not configured to the network. At step <NUM>, the UE assistance information is sent to update the change in the MR-DC capability of the UE <NUM>.

<FIG> is a sequence diagram for the flow <NUM> disclosed in <FIG>, for indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, and the UE-assistance information is configured to the network, according to an embodiment as disclosed herein. As shown in the <FIG>, the UE <NUM> is an MR-DC capable UE at step <NUM>, and the UE <NUM> is in the RRC connected state at step <NUM>. The trigger to disable/enable the MR-DC capability of the UE <NUM> is received by the UE <NUM> at steps <NUM> and <NUM>. As seen in <FIG> the UE-assistance information is configured to the network. The trigger to disable/enable the MR-DC capability of the UE <NUM> is received. After receiving the trigger for the change in the MR-DC capability of the UE <NUM>, the request for change in the MR-DC capability of the UE <NUM> is sent to the eNB <NUM> at step <NUM>, and in response the SN <NUM> is released by the eNB <NUM> at step <NUM>. The RRC connection update is also received by the UE <NUM> from the eNB <NUM> at step <NUM>. The UE <NUM> thus is in the idle mode at steps <NUM> and <NUM>. The procedure explained <FIG> and <FIG> for sending the TAU procedures is followed for the UE <NUM>.

<FIG> is a sequence diagram for conventional method indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, and the UE-assistance information is not configured to the network, according to an embodiment as disclosed herein. <FIG> explains a scenario where the UE <NUM> is in the connected mode and is MR-DC enabled. A data path is established for the UE <NUM>, the eNB <NUM>, and the gNB <NUM>. The MR-DC capability of the UE <NUM> is disabled upon receiving the trigger for disabling the MR-DC capability of the UE <NUM>. As seen in the <FIG> the MR-DC capability of the UE <NUM> is disabled/enabled upon occurrence of the local trigger without sending the TAU to the SN <NUM> and MN <NUM>. The disabling/enabling of the MR-DC capability of the UE <NUM> before sending the TAU procedure results in loss of data from the SN <NUM> as the change in the MR-DC capability of the SN <NUM> is not updated and is sending the data to the UE <NUM>. Further for conventional application the network resources are utilized unnecessarily by the SN for retransmitting as the transmission results into a failure. In an example the SN <NUM> sends SCG reconfiguration messages to the UE <NUM>. However, the UE <NUM> is unable to recognize the SCG reconfiguration messages sent by the SN <NUM> as the UE <NUM> is MR-DC disabled. Thus as discussed above, changing the MR-DC capability of the UE <NUM> before sending the TAU messages to the MN <NUM> and the SN <NUM>, while the UE <NUM> is in connected mode, results into plurality of disadvantages.

<FIG> is a sequence diagram for conventional method indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, and the UE-assistance information is not configured to the network, according to an embodiment as disclosed herein. <FIG> explains a scenario where the UE <NUM> is in the connected mode and is MR-DC enabled. The MR-DC capability of the UE <NUM> is disabled upon receiving the trigger for disabling the MR-DC capability of the UE <NUM>. As seen in the <FIG> the MR-DC capability of the UE <NUM> is disabled/enabled upon occurrence of the local trigger after sending the TAU message to the MME <NUM>. Here the MME <NUM> is aware about the change in the MR-DC capability of the UE <NUM> due to the TAU messages; however the MN <NUM> and the SN <NUM> are not aware of the change in the MR-DC capability. In an example the SN <NUM> sends SCG reconfiguration messages to the UE <NUM>. However the UE <NUM> is unable to recognize the SCG reconfiguration messages sent by the SN <NUM> as the UE <NUM> is MR-DC disabled. Thus as discussed above, changing the MR-DC capability of the UE <NUM> after sending the TAU messages to the MME <NUM>, while the UE is in connected mode, results into plurality of disadvantages.

<FIG> is a sequence diagram for conventional method indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, and the UE-assistance information is not configured to the network, according to an embodiment as disclosed herein. <FIG> explains a scenario where the UE <NUM> is in the connected mode and is MR-DC enabled. As seen in the <FIG> the trigger to disable the MR-DC capability of the UE <NUM> is received. The TAU messages are sent to the MME <NUM> indicating the change in the MR-DC capability of the UE <NUM>. The UE capability enquiry is sent by the MME <NUM> and the UE <NUM> and the response is received. After receiving the response the MR-DC capability of the UE <NUM> is disabled. However, the SN <NUM> releases the SCG reconfiguration upon receiving the response that the MR-DC capability of the UE <NUM> is disabled. This results into RLF as the UE <NUM> is already MR-DC disabled.

<FIG> is a flow diagram for conventional method indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. The figure states that when the local trigger to change the MR-DC capability is received a local RRC release is done. The UE <NUM> enters the idle mode by performing the local RRC release. The TAU procedure, an RACH procedure and a security procedure is then sent to the eNB <NUM> and the MME <NUM>. Thus the eNB <NUM> and the MME <NUM> are aware of the MR-DC capability change of the UE <NUM>. The MR-DC capability of the UE <NUM> is then disabled. (NR modem is disabled at the UE side). The conventional method as explained above has multiple disadvantages and there is no specific method for moving the UE <NUM> into the idle mode. However the conventional method results in RLF at the network side. Till the time the RLF is detected at the network side, the network continues to send the data to the device which results in loss of data. This also results in wastage of the network resources. The network has to retransmit those packets which are missed by the UE due to the local release. The method as explained in <FIG> provides a solution to the problems existing with the conventional methods.

<FIG> is a flow diagram <NUM> for the proposed method, when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. At step <NUM> the trigger for disabling the MR-DC is met. At step <NUM> the MR-DC capability connectivity regulator <NUM> determines whether a dual connectivity (DC) for a secondary node (SN) <NUM> is configured. The method then proceeds to step <NUM> if the DC for the SN <NUM> is configured and to step <NUM> if the DC for the SN <NUM> is not configured.

In an embodiment if the DC for the SN <NUM> is not configured then at step <NUM> the TAU message is triggered indicating the change in the MR-DC capability of the UE.

In an embodiment if the DC for the SN <NUM> is configured for the UE then at step <NUM> a secondary cell group (SCG) failure indication message is triggered. At step <NUM> a timer to receive an acknowledgement of the SCG failure indication message is initiated. At step <NUM> the MR-DC capability connectivity regulator <NUM> determines that the timer is expired and the acknowledgement of the SCG failure indication message is not received or the acknowledgement of the SCG failure indication message is received before expiry of the timer. At step <NUM>, after receiving the acknowledgement, the monitoring of the downlink of SN <NUM> is stopped. At step <NUM>, TAU message comprising the indication of the change in the MR-DC capability of the UE <NUM> is triggered to the wireless node.

<FIG> is a sequence diagram for method flow <NUM>, indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. As seen in the <FIG> the UE is in the RRC connected state at step <NUM>. A trigger to disable the MR-DC capability of the UE <NUM> is received. As can be seen the SN <NUM> is configured. The trigger to disable the MR-DC capability of the UE <NUM> is received. The UE <NUM> sends the SCG failure indication to the eNB <NUM> at step <NUM> and waits for an acknowledgement from the SN <NUM> by imitating the timer. The eNB <NUM> after receiving the SCG failure indication, send the acknowledgement to the UE <NUM> at step <NUM>. The UE <NUM> then stops monitoring the downlink for the SCG and the UE <NUM> is then MR-DC disabled. The TAU messages are sent to the MME <NUM> indicating the change in the MR-DC capability of the UE <NUM> at step <NUM>. As a result of this the data loss from the eNB <NUM> is elimination. Further there is no redundant usage of the network resources. The RLF problems are also eliminated by the above discussed method. At steps <NUM>, the eNB <NUM> sends to the MME <NUM> a message indicating that no UE radio capability information included. Then, at step <NUM>, the MME <NUM> sends to the eNB <NUM> a UE radio capability match request. The eNB <NUM> sends to the UE <NUM> a UE capability enquiry at step <NUM>, and the UE <NUM> sends to the eNB <NUM> UE capability information (MR-DC disable) at step <NUM>.

<FIG> is a flow diagram <NUM> for indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. At step <NUM> the trigger for disabling the MR-DC is met. At <NUM> the MR-DC capability connectivity regulator <NUM> determines whether a dual capability (DC) for the SN <NUM> is configured. The method then proceeds to step <NUM> if the DC for the SN <NUM> is configured and to step <NUM> if the DC is not configured.

In an embodiment if the DC for the SN <NUM> is configured for the UE then at step <NUM> it is determined whether an MR is configured for the network or not. The method proceeds to step <NUM> if the MR is configured and to step <NUM> if the MR is not configured. At step <NUM> the reporting of the SCG cells and at least one MR is sent, indicating that no SCG cells are available. At step <NUM> a timer is initiated to wait for 'x' units of time. At step <NUM> it is determined that the timer is expired and the RRC reconfiguration is received is not received or the RRC reconfiguration is received before expiry of the timer. If the RRC reconfiguration is received before expiry of the `x' units of time then the method proceeds to step <NUM> and if the RRC reconfiguration is not received before expiry of the timer then the step proceeds to step <NUM>.

<FIG> is a continuation of flow diagram <NUM> of <FIG>. At <NUM>, it is determined whether the SCG configuration is present or not. The method proceeds to step <NUM> if the SCG configuration is not present and to step <NUM> if the SCG configuration is present. At step <NUM> the RRC reconfiguration is processed as per the specification and the TAU messages is triggered by the TAU trigger comprising the indication of the change in the MR DC capability of the UE. At step <NUM> it is determined whether the SCG failure indication is already triggered. The method proceeds to step <NUM> if the SCG failure indication is already triggered and to step <NUM> if the SCG failure indication is not triggered. At step <NUM> the SCG container is ignored. At step <NUM> the RRC reconfiguration is processed as per the specification and the TAU messages is triggered by the TAU trigger comprising the indication of the change in the MR DC capability of the UE.

<FIG> is a continuation of flow diagram <NUM> of <FIG> and <FIG>. <FIG> starts with step <NUM>. At step <NUM> a SCG failure indication trigger is received. The method then proceeds to step <NUM>. At step <NUM> it is determined that the timer is expired, and the acknowledgement of the SCG failure indication message is not received or the acknowledgement of the SCG failure indication message is received before expiry of the timer at step <NUM>. At step <NUM> after receiving the acknowledgement the monitoring of the downlink of SN is stopped. At step <NUM>, the TAU message comprising the indication of the change in the MR-DC capability of the UE is triggered to the wireless node.

<FIG> is a sequence diagram for method flow <NUM>, indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. As seen in the <FIG> the UE is in the RRC connected state. A trigger to disable the MR-DC capability of the UE <NUM> is received. As can be seen the SN <NUM> is configured. The trigger to disable the MR-DC capability of the UE <NUM> is received. The UE <NUM> sends a Measurement Report (MR) to the eNB indicating that the trigger to disable the MR-DC capability of the UE <NUM>. The UE <NUM> the sends the SCG failure indication to the eNB <NUM> and waits for an acknowledgement from the SN <NUM> by imitating a timer. The eNB <NUM> after receiving the SCG failure indication, send the acknowledgement to the UE <NUM>. The UE <NUM> then stops monitoring the downlink for the SCG and the UE <NUM> is then MR-DC disabled. The TAU messages are sent to the MME indicating the change in the MR-DC capability of the UE <NUM>. The RACH procedure and the security procedure are then followed as discussed above. As a result of this the data loss from the eNB106 is elimination. Further there is no redundant usage of the network resources. The RLF problems are also eliminated by the above discussed method.

<FIG> is a flow diagram <NUM> for indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. At step <NUM>, it is determined whether SN <NUM> configuration is present or not. The method is stopped if the SN <NUM> configuration is not present and proceeds to step <NUM> if the SN configuration is present. At <NUM>, the SCG container is ignored in the message and the method is then stopped.

<FIG> is a sequence diagram for the flow <NUM> shown in <FIG>. As shown in the <FIG>, the UE is in RRC connected state with the eNB <NUM> at step <NUM>. The trigger to disable the MR-DC of the UE <NUM> is received at step <NUM>. The UE <NUM> sends the TAU messages to the MME <NUM> at step <NUM>. The eNB send enquiry for the UE capability and receives a response by the UE <NUM>. The MR-DC capability of the UE <NUM> is disabled after sending the response at step <NUM>. The RRC reconfiguration is released and the SCG container is ignored in the message. Thus the above method eliminates RLF on the MN <NUM>. At steps <NUM>, the eNB <NUM> sends to the MME <NUM> a message indicating that no UE radio capability information included. Then, at step <NUM>, the MME <NUM> sends to the eNB <NUM> a UE radio capability match request. The eNB <NUM> sends to the UE <NUM> an RRC connection reconfiguration (SN related measurements/reconfigurations) at step <NUM>, and the UE <NUM> sends to the eNB <NUM> an RRC reconfiguration complete (ignore SN container) at step <NUM>.

<FIG> is a flow diagram <NUM> for indicating the change in the MR-DC capability of the UE <NUM> when the UE <NUM> is in the connected mode, according to an embodiment as disclosed herein. At step <NUM>, it is determined whether the SN configuration is present or not. The method proceeds to step <NUM> if the SCG configuration is not present and to step <NUM> if the SCG configuration is present. At step <NUM> the UE <NUM> waits for the capability update procedure to be completed. At step <NUM> it is determined whether the SCG failure indication is already triggered. The method proceeds to step <NUM> if the SCG failure indication is already triggered and to step <NUM> if the SCG failure indication is not triggered. At step <NUM> the SCG container is ignored. At step <NUM> a secondary cell group (SCG) failure indication message is triggered. At step <NUM> a timer to receive an acknowledgement of the SCG failure indication message is initiated. At step <NUM> it is determined that the timer is expired and the acknowledgement of the SCG failure indication message is not received or the acknowledgement of the SCG failure indication message is received before expiry of the timer. At step <NUM> after receiving the acknowledgement the monitoring of the downlink of SN is stopped. At step <NUM> a TAU message comprising the indication of the change in the MR-DC capability of the UE <NUM> is triggered to the wireless node.

<FIG> is a sequence diagram for the flow <NUM> shown in <FIG>. As shown in the <FIG>, the UE <NUM> is in RRC connected state with the eNB <NUM>. The trigger to disable the MR-DC of the UE <NUM> is received. The UE <NUM> sends the TAU messages to the MME. The eNB send enquiry for the UE capability and receives a response from the UE <NUM>. The MR-DC capability of the UE <NUM> is disabled after sending the response. The RRC reconfiguration is released. The SCG failure indication message is triggered and the acknowledgement is received by the UE <NUM>. The UE <NUM> stops monitoring the downlink for the SCG. The SN <NUM> container is ignored. Thus the above said method eliminates the problem RLF on the MN.

Claim 1:
A method for indicating a change in multi-radio access technology, RAT, dual connectivity, MR-DC, capability by a user equipment, UE, comprising:
detecting, by the UE, based on a local trigger, a change in the MR-DC capability of the UE that has occurred;
identifying, by the UE, an operation mode of the UE, the operation mode being one of an idle mode and a connected mode;
in response to the operation mode being the idle mode:
holding, by the UE, transmission of a tracking area update, TAU, message, detecting, by the UE, an event, and identifying a validity of the change in the MR-DC capability of the UE after detecting the event, and sending a TAU message providing, to a first network node, information indicating that the MR-DC capability of the UE is changed based on a result of the identification; and
in response to the operation mode being the connected mode:
identifying, by the UE, whether UE-assistance information is configured by the first network node, and triggering, by a TAU trigger (<NUM>) of the UE, a message providing, to the first network node, the information indicating the MR-DC capability of the UE is changed based on the UE-assistance information in response to identifying that the UE-assistance information is configured by the first network node.