Terminal device and method

Abstract

[0003] Embodiments of the present disclosure relate to a method, apparatus, and medium for communication. The communication method includes, at a terminal device, receiving a first instruction to deactivate a cell group of a second network device from a first network device, where the first network device is a master node serving the terminal device and the second network device is a secondary node serving the terminal device. The method further includes discarding data units of a data link layer of the terminal device used for transmission in the cell group.

Description

[Technical field]

[0001] TECHNICAL FIELD Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to methods, apparatus and media for communication. [Background technology]

[0002] Dual Connectivity is an operating mode in which a terminal device (e.g., a user equipment (UE)) can be configured to utilize radio resources provided by two network devices (e.g., two base stations). A first network device serves the terminal device as a master node (MN) and a second network device serves the terminal device as a secondary node (SN). The MN and SN are connected via a non-ideal backhaul by a network interface, and at least the MN is connected to a core network.

[0003] MNs and SNs may be associated with one or more serving cells. In a Carrier Aggregation (CA) scenario, MNs and SNs may each be associated with a group of serving cells including a Primary Cell (PCell) and optionally one or more Secondary Cells (SCells). The serving cell group associated with an MN is called a Master Cell Group (MCG), and the serving cell group associated with an SN is called a Secondary Cell Group (MCG). The SCG may need to be suspended in some cases, for example to reduce power consumption. However, a mechanism for SCG suspension has not yet been specified. Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, the exemplary embodiments of the present disclosure provide an SCG suspension solution. [Means for solving the problem]

[0005] In a first aspect, a communication method is provided, the method including receiving, in a terminal device, a first instruction from a first network device to deactivate a cell group of a second network device, and discarding a data unit of a data link layer of the terminal device used for transmission in the cell group, the first network device being a master node serving the terminal device, and the second network device being a secondary node serving the terminal device.

[0006] In a second aspect, a communication method is provided, the method including receiving, in a terminal device, an instruction from a first network device to activate a cell group of a second network device, starting a timer having an upper limit value set by the first network device, and initiating a random access procedure in a primary cell of the cell group, the first network device being a master node serving the terminal device and the second network device being a secondary node serving the terminal device.

[0007] In a third aspect, there is provided a terminal device, the network device comprising a processor unit and a memory, coupled to the processor unit, having instructions stored thereon, the instructions, when executed by the processor unit, causing the device to perform a method according to the first aspect.

[0008] In a fourth aspect there is provided a terminal device comprising a processor unit and a memory coupled to the processor unit and having instructions stored thereon which, when executed by the processor unit, cause the device to perform a method according to the second aspect.

[0009] In a fifth aspect, there is provided a computer readable medium having stored thereon instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to the first aspect.

[0010] In a sixth aspect, there is provided a computer readable medium having stored thereon instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to the second aspect.

[0011] Other features of the present disclosure will become readily apparent from the following description. [Brief description of the drawings]

[0012] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of several exemplary embodiments of the present disclosure in the accompanying drawings.

[0013] [Figure 1] FIG. 1 is a block diagram of a communication environment in which embodiments of the present disclosure can be implemented.

[0014] [Figure 2A] 1 is a signaling chart illustrating a process of triggering SCG suspension in accordance with some embodiments of the present disclosure. [Figure 2B] 1 is a signaling chart illustrating a process of triggering SCG suspension in accordance with some embodiments of the present disclosure.

[0015] [Diagram 3] 1 is a signaling chart showing a process of SCG suspension according to some embodiments of the present disclosure.

[0016] [Figure 4] FIG. 2 is a block diagram of network protocol layer entities established in a terminal device in accordance with some embodiments of the present disclosure.

[0017] [Diagram 5] FIG. 2 is a block diagram of network protocol layer entities established in a terminal device in accordance with some embodiments of the present disclosure.

[0018] [Figure 6A] 1 is a signaling chart illustrating a process of triggering SCG restart according to some embodiments of the present disclosure. [Figure 6B] 1 is a signaling chart illustrating a process of triggering SCG restart according to some embodiments of the present disclosure.

[0019] [Figure 7] 1 is a signaling chart illustrating the process of SCG restart, according to some embodiments of the present disclosure.

[0020] [Figure 8A] FIG. 13 is a schematic diagram illustrating an example message indicating a failure to restart an SCG, in accordance with some embodiments of the present disclosure. [Figure 8B] FIG. 13 is a schematic diagram illustrating an example message indicating a failure to restart an SCG, in accordance with some embodiments of the present disclosure.

[0021] [Figure 9] 1 illustrates another exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0022] [Figure 10] 1 illustrates another exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0023] [Figure 11] FIG. 1 is a schematic block diagram of an apparatus suitable for practicing embodiments of the present disclosure.

[0024] Throughout the drawings, the same or similar reference numbers represent the same or similar elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are merely described for illustrative purposes to aid those skilled in the art in understanding and implementing the present disclosure, and are not intended to imply any limitations on the scope of the present disclosure. The present disclosure described herein can be implemented in a variety of ways other than those described below.

[0026] In the following description and claims, unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0027] As used herein, the term "network equipment" refers to equipment capable of providing or hosting a cell or coverage through which terminal equipment can communicate. Examples of network equipment include, but are not limited to, Node B (NB or NB), Evolved Node B (eNodeB or eNB), Node B for new radio access (gNB), Remote Radio Head (RRU), Radio Head (RH), Remote Radio Head (RRH), low power nodes such as femto nodes, pico nodes, satellite network equipment, aircraft network equipment, etc. In the following, for the purpose of discussion, some exemplary embodiments are described with reference to an eNB as an example of a network equipment.

[0028] In this specification, the term "terminal device" refers to any device having wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, user equipment (UE), personal computers, desktops, mobile phones, mobile phones, smartphones, personal digital assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices or evolved MTC (eMTC) devices, vehicle-mounted devices for V2X communication (where X represents pedestrians, vehicles, or infrastructure / networks), imaging devices such as digital cameras, gaming devices, music storage and playback devices, Internet devices that enable wireless / wired Internet access and browsing, etc. In the following description, the terms "terminal device", "communication device", "terminal", "user terminal", and "UE" may be used interchangeably.

[0029] In one embodiment, the terminal device may be connected to a first network device and a second network device. One of the first network device and the second network device may be a master node, and the other may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, the first network device may be a first RAT device, and the second network device may be a second RAT device. In one embodiment, the first RAT device is an eNB, and the second RAT device is a gNB. Information related to the different RATs may be transmitted to the terminal device from at least one of the first network device and the second network device. In one embodiment, the first information may be transmitted from the first network device to the terminal device, and the second information may be transmitted from the second network device directly to the terminal device or via the first network device. In one embodiment, information related to the configuration of the terminal device set by the second network device may be transmitted from the second network device via the first network device. Information related to the reconfiguration of the terminal device set by the second network device may be transmitted from the second network device directly to the terminal device or via the first network device.

[0030] Communications discussed herein may conform to any suitable standard, including, but not limited to, New Radio Access (NR), Long Term Evolution (LTE), LTE Evolution (LTE-Evolution), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, Global System for Mobile Communications (GSM), and the like. Furthermore, communications may be performed according to any currently known or future developed generation of communications protocols. Examples of communications protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communications protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above, as well as other wireless networks and radio technologies.

[0031] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. The term "comprising" and variations thereof are intended to be open ended meaning "including, but not limited to." The term "based on" is intended to mean "based at least in part on." The terms "one embodiment" and "one embodiment" are intended to mean "at least one embodiment." The term "another embodiment" is intended to mean "at least one other embodiment." Terms such as "first," "second," and the like may refer to different objects or the same object. The following content may include other definitions, both explicit and implicit.

[0032] In some instances, values, procedures, or devices are referred to as "optimum," "lowest," "highest," "minimum," "maximum," etc. It is understood that such descriptions are intended to indicate choices among multiple functional alternatives that may be used, and that such choices are not necessarily better, smaller, higher, or more preferred than other choices. Example Environment

[0033] 1 illustrates an example communication network 100 in which an example embodiment of the present disclosure may be implemented. In the example of FIG. 1, multiple network devices 110, 120 are deployed and serve a terminal device 130. The network device 110 serves the terminal device 130 as a MN, and the network device 120 serves the terminal device 130 as a SN.

[0034] The serving areas of the network devices 110 and 120 are referred to as cells. As shown in Fig. 1, the cell group of the network device 110 includes a primary cell 150-1 and a secondary cell 150-2. Since the network device 110 functions as an MN, the cell group of the network device 110 is referred to as an MCG 150, and the primary cell 150-1 is also referred to as a PCell 150-1.

[0035] The cell group of the network device 120 includes a primary cell 160-1 and a secondary cell 160-2. Since the network device 120 functions as an SN, the cell group of the network device 120 is referred to as an SCG 160, and the primary cell 160-1 is also referred to as a PSCell 160-1. Note that the PCell 150-1 and the PSCell 160-1 may be collectively referred to as an SpCell.

[0036] It should be understood that the number of SCells in FIG. 1 is shown for illustrative purposes and does not imply any limitation to the present disclosure. The network devices 110, 120 may provide any suitable number of SCells to serve the terminal device 130.

[0037] Communications between terminal device 130 and network devices 110, 120 may be performed according to any suitable communications protocol. Communications in the direction from terminal device 130 to network devices 110 or 120 are referred to as UL communications, and communications in the reverse direction from network devices 110 or 120 to terminal device 130 are referred to as DL communications. Terminal device 130 may move between the coverage areas of network devices 110, 120, and possibly other network devices.

[0038] In UL communication, the terminal device 130 may transmit UL data and control information to the network device 110 or 120 over a UL channel. In some examples, the UL data may be transmitted on a physical uplink shared channel (PUSCH) and / or any other UL channel available for data transmission. In some examples, the UL control information may be transmitted on a physical uplink control channel (PUCCH) and / or any other UL channel available for control information transmission. In DL transmission, the network device 110 or 120 may transmit DL data and control information to the terminal device 130 over a DL channel. In some examples, the DL data may be transmitted on a physical downlink shared channel (PDSCH) and / or any other DL channel available for data transmission. In some examples, the DL control information may be transmitted on a physical uplink control channel (PDCCH) and / or any other DL channel available for control information transmission.

[0039] The DC provided by the network devices 110 and 120 may include any suitable type of multi-radio dual connectivity (MR-DC), including, but not limited to, E-UTRA (Evolved Universal Terrestrial Radio Access)-NR dual connectivity (EN-DC), NGEN-DC, and NR-DC. In the case of EN-DC, the network device 110 is an eNB and the network device 120 is a gNB. In the case of NGEN-DC, the network device 110 is a gNB and the network device 120 is an eNB. In the case of NR-DC, both the network devices 110 and 120 are gNBs.

[0040] It should be understood that the number and types of devices in Figure 1 are shown for illustrative purposes and are not intended to imply any limitations on the present disclosure. The communication environment 100 may include any suitable number of network devices and / or terminal devices suitable for carrying out implementations of the present disclosure. Furthermore, the communication environment 100 may include any devices other than network devices and terminal devices, such as core network elements, which are omitted herein to avoid obscuring the present disclosure.

[0041] In a communication environment, power consumption of a terminal device (such as a UE) is a major issue. Existing solutions for power saving for CA scenarios include activation and deactivation of an SCell. To enable reasonable power consumption (e.g., battery consumption) of a UE during CA configuration, a mechanism for activation / deactivation of an SCell is supported. When an SCell is deactivated, the UE does not need to receive the corresponding PDCCH or PDSCH, cannot transmit in the corresponding uplink, and does not need to perform a Channel Quality Indicator (CQI) measurement. Conversely, when an SCell is activated, the UE must receive the PDSCH and PDCCH (if the UE is configured to monitor the PDCCH from this SCell) and is expected to be able to perform a CQI measurement.

[0042] Existing solutions on power saving for CA scenarios further include Scell ​​Dormancy. To enable fast activation of SCell during CA configuration, one dormant bandwidth part (BWP) can be configured on the SCell. If the active BWP of an activated SCell is a dormant BWP, the UE stops monitoring the PDCCH on the SCell but continues to measure Channel State Information (CSI), perform Automatic Gain Control (AGC) and beam management (if configured). Downlink Control Information (DCI) is used to control entering / leaving the dormant BWP of one or more SCells or one or more groups of SCells. The dormant BWP is one of the dedicated BWPs of the UE configured by the network via dedicated Radio Resource Control (RRC) signaling. Dormant BWPs cannot be configured for SpCell and PUCCH SCells.

[0043] Power saving solutions are also needed for DC scenarios. As mentioned above, SCG suspension may be required in some cases. Take EN-DC as an example. UE and network power consumption is a major challenge to maintain two radio links simultaneously. For example, UE power consumption in NR networks may be three to four times that of UE power consumption in LTE networks in some cases. In EN-DC deployment, MN provides base coverage. When UE data rate requirements change dynamically, e.g., from high to low, deactivating or suspending SN to reduce power consumption is worth considering. Therefore, an efficient SCG deactivation mechanism should be defined. This efficient SCG deactivation mechanism may also be applied to other MR-DC deployments, including but not limited to NGEN-DC and NR-DC. The terms "SCG suspension" and "SCG deactivation" are used interchangeably herein.

[0044] Three options are proposed for modeling SCG suspension. In option 1, all serving cells associated with the SN, including PScells and SCells, are activated and the active BWP is configured as a dormant BWP. The drawback of this option is that at least two RRC-configured BWPs must be configured for all serving cells. In option 2, all serving cells associated with the SN, including PScells and SCells, are deactivated. The drawback of this option is that data communication recovery takes longer. In option 3, the SCells of the SCG must be deactivated and the PScells of the SCG must be activated and the active BWP is configured as a dormant BWP.

[0045] As can be seen from the above, unlike SCell activation / deactivation and SCell suspension (where there is no higher layer operation because the PSCell can maintain data transmission), in SCG suspension, neither the PSCell nor the SCell can send or receive data. Therefore, for SCG suspension, it is necessary to specify higher layer operations. However, the SCG suspension mechanism is not clear, and only the operation of the Medium Access Control (MAC) layer has been roughly discussed. At present, there is no concrete solution for an efficient SCG suspension mechanism.

[0046] Furthermore, after the SCG is suspended or deactivated, the MN or SN may decide to resume or activate the suspended SCG as needed. In this specification, the resumption of the suspended SCG may be referred to as "SCG resumption" or "SCG activation". Therefore, an efficient and robust SCG resumption mechanism should be defined. This efficient and robust SCG resumption may be applied to various MR-DC deployments, including but not limited to EN-DC, NGEN-DC, and NR-DC deployments.

[0047] According to an exemplary embodiment of the present disclosure, a solution for SCG suspension is provided, in which a first network device serves a terminal device as a MN and a second network device serves the terminal device as a SN. The terminal device receives an instruction from the first network device to deactivate a cell group, i.e., an SCG, of the second network device. This instruction is also referred to as an SCG suspension instruction. Upon receiving the SCG suspension instruction, the terminal device performs a procedure to suspend the SCG. The terminal device discards at least data units of the terminal device's data link layer. The data units are used for transmission in the SCG. Discarding data units that become stale when the SCG is resumed is beneficial to achieving a reliable SCG suspension and also to achieving an efficient SCG resumption.

[0048] In some embodiments, a solution for SCG resumption is provided. In this solution, a terminal device receives an instruction from a first network device to activate a previously deactivated SCG. This instruction is also referred to as an SCG resumption instruction. Upon receiving the SCG resumption instruction, the terminal device performs a procedure to resume the SCG. The terminal device starts a timer and initiates a random access procedure in a PSCell of the SCG. The timer can be used by the terminal device to determine whether the SCG resumption is successful. If the SCG resumption is not successful, the terminal device may notify the first network device of the failure. In this way, a robust SCG resumption can be realized. SCG Suspension Exemplary Process

[0049] Hereinafter, some exemplary embodiments of the present disclosure will be described in detail. The SCG suspension may be triggered or initiated by the MN or SN. FIGS. 2A and 2B are signaling charts showing processes 200 and 205 for triggering the SCG suspension according to some embodiments of the present disclosure. For the purpose of discussion, processes 200 and 205 will be described with reference to FIG. 1. Processes 200 and 205 may involve the terminal device 130, the network device 110, and the network device 120. In process 200 of FIG. 2A, the network device 110 operating as the MN initiates the SCG suspension. In process 205 of FIG. 2B, the network device 120 operating as the SN initiates the SCG suspension.

[0050] First, process 200 in FIG. 2A will be discussed. As a prerequisite or trigger condition, in some embodiments, the network device 120 may send an activity notification to the network device 110 (202). The activity notification may notify the network device 110 that the network device 120 is in an inactive state. Alternatively, or in addition, in some embodiments, the network device 120 may send a report on the data usage of the secondary RAT to the network device 110 (204). The report may be sent periodically.

[0051] Based on the activity notification and / or the report on the data usage of the secondary RAT, the network device 110 determines to initiate the SCG suspension (206). For example, if the activity notification indicates that the network device 120 has been in an inactive state for a certain period, or if the report indicates that the network device 110 can handle the traffic of the terminal device 130, the network device 110 may determine to initiate the SCG suspension.

[0052] Network device 110 then sends (208) a request to network device 120 to suspend or deactivate the SCG of network device 120. This request may be referred to as an SCG stop request. Upon receiving the SCG suspension request, network device 120 sends (210) a response to the SCG suspension request to network device 110. This response may be referred to as an SCG suspension response.

[0053] The network device 110 transmits (212) a message to the terminal device 130 indicating an SCG suspension. This message may be referred to as an SCG suspension message. In some embodiments, upon receiving the SCG suspension message, the terminal device 130 may transmit (214) a response to the network device 110. As an example, the SCG suspension message may be an RRC Reconfiguration message and the response may be an RRC Reconfiguration Complete message. Other messages are also possible, such as messages specific to SCG suspension.

[0054] Upon receiving the response from the terminal device 130, the network device 110 sends (216) a message to the network device 120 notifying the SCG suspension. By way of example, this message may be a SgNBReconfigurationComplete message.

[0055] Upon receiving the SCG suspension message from network device 110, terminal device 130 performs a procedure to suspend the SCG of network device 120 (218). This procedure may be referred to herein as an SCG suspension procedure. The SCG suspension procedure is described below with reference to Figures 3 and 4.

[0056] It should be understood that the order of operations shown in Figure 2A is for illustrative purposes only and does not imply any limitation on the scope of the present disclosure. For example, upon receiving an SCG suspension message, terminal device 130 may perform an SCG suspension procedure (218) and then transmit a response to network device 110 (214). Alternatively, upon receiving an SCG suspension message, terminal device 130 may perform an SCG suspension procedure (218) and simultaneously transmit a response to network device 110 (214).

[0057] 2B, in FIG. 2B, the network device 120 acting as an SN initiates an SCG suspension. In process 205 of FIG. 2B, the network device 120 decides to initiate an SCG suspension (220). For example, if the network device 120 has not processed traffic from the terminal device 130 for a certain period of time, the network device 120 may decide to suspend the SCG.

[0058] Network device 120 sends a request to network device 110 to suspend the SCG (222). This request may also be referred to as an SCG suspension request. Upon receiving the SCG suspension request, network device 110 sends a confirmation for the SCG suspension request to network device 120 (224). This may also be referred to as an SCG suspension confirmation.

[0059] In addition, network device 110 transmits an SCG suspension request to terminal device 130 (212). Operations denoted with the same reference symbols as in Fig. 2A are the same as those described with reference to Fig. 2A, and therefore will not be described repeatedly here.

[0060] As can be seen from the processes 200, 205, whether the SCG suspension is initiated by the MN or the SN, it is the MN that indicates to the terminal device 130 to suspend the SCG associated with the SN. Figure 3 is a signaling chart illustrating a process 300 of SCG suspension according to some embodiments of the present disclosure. For purposes of discussion, the process 300 will be described with reference to Figure 1. The process 300 may involve the terminal device 130 and the network device 110 acting as the MN.

[0061] In process 300, network device 110 sends (302) an instruction to end device 130 to suspend or deactivate SCG 160 of network device 120. For example, network device 110 may send the instruction when it determines to initiate an SCG suspension (as shown in process 200). As another example, network device 110 may send the instruction when it receives an SCG suspension request from network device 120 (as shown in process 205).

[0062] This indication may also be referred to herein as a "first indication" or an "SCG suspension indication." The SCG suspension indication may be implemented by any suitable signaling. In some embodiments, the SCG stop indication may be included in an RRC message. In these embodiments, upon receiving the RRC message, the terminal device 130 may send a corresponding RRC message to the network device 110 in response (304). As an example, the network device 110 may send an RRCReconfiguration message to indicate the SCG suspension. In response, the terminal device 130 may send an RRCReconfigurationComplete message to the network device 110 in response.

[0063] In such an embodiment, RRC signaling is used to convey the SCG suspension indication, thus reducing communication between different protocol layers in the terminal device 130 and improving the efficiency of the SCG suspension.

[0064] Upon receiving the SCG suspension indication, the terminal device 130 executes an SCG suspension procedure. Specifically, the terminal device 130 discards data units for transmission in the SCG (306). The data units are buffered in the data link layer of the terminal device 130.

[0065] The buffered data units include buffered signaling for signaling radio bearer 3 (SRB3), which is a direct signaling radio bearer (SRB) between terminal device 130 and network device 120. When the SCG of network device 120 resumes from suspension, the buffered signaling will be stale and will mislead network device 120. The stale signaling will mislead network device 120. To avoid stale signaling being sent to network device 120 when the SCG resumes, the buffered signaling should be discarded upon receiving an SCG suspension indication.

[0066] Similarly, the buffered data units include buffered data for a Data Radio Bearer (DRB) between the terminal device 130 and the network device 120. The buffered data is stale and unusable when the SCG of the network device 120 resumes from suspension. To avoid stale and unusable data being sent to the network device 120 when the SCG resumes, the buffered data should be discarded upon receiving an SCG suspension indication.

[0067] To better understand the SCG suspension procedure of the present disclosure, an example of radio protocol architecture in MR-DC is described with reference to Figures 4 and 5. On the terminal device 130 side, there are three types of DRBs: MCG bearer, split bearer, and SCG bearer. MCG bearer refers to a radio bearer with a Radio Link Control (RLC) bearer (two RLC bearers in case of CA packet duplication) in MCG only. SCG bearer refers to a radio bearer with a RLC bearer (two RLC bearers in case of CA packet duplication) in SCG only. Split bearer refers to a radio bearer with an RLC bearer in both MCG and SCG.

[0068] FIG. 4 is a block diagram of data link layer entities established in a terminal device 130 according to some embodiments of the present disclosure. The data link layer entities shown in FIG. 4 are based on the EN-DC radio protocol architecture. In the MAC layer, an E-UTRA MAC entity 411 may be established for both the MCG bearer and the split bearer. Also, an NR MAC entity 421 may be established for both the SCG bearer and the split bearer. In the RLC layer, an E-UTRA RLC entity 412 may be established for the MCG bearer. Also, a separate E-UTRA RLC entity 431 may be established for the split bearer. Similarly, an NR RLC entity 422 may be established for the SCG bearer, and another NR RLC entity 432 may be established for the split bearer. At the Packet Data Convergence Protocol (PDCP) layer, an E-UTRA / NR PDCP entity 413 may be established for the MCG bearer, an NR PDCP entity 433 may be established for the split bearer, and an NR PDCP entity 423 may be established for the SCG bearer.

[0069] FIG. 5 is a block diagram of data link layer entities established in a terminal device 130 according to some embodiments of the present disclosure. The data link layer entities shown in FIG. 5 are based on the radio protocol architecture in MR-DC with 5G core network (5GC), such as NGEN-DC and NR-DC. In the MAC layer, a MN MAC entity 511 may be established for both the MCG bearer and the split bearer, and a SN MAC entity 521 may be established for both the SCG bearer and the split bearer. In the RLC layer, a MN RLC entity 512 may be established for the MCG bearer, and another MN RLC entity 531 may be established for the split bearer. Similarly, a SN RLC entity 522 may be established for the SCG bearer, and another SN RLC entity 532 may be established for the split bearer. In the PDCP layer, an NR PDCP entity 513 may be established for the MCG bearer, another NR PDCP entity 533 may be established for the split bearer, and a further NR PDCP entity 523 may be established for the SCG bearer. Different from the architecture shown in Figure 4, there is a Service Data Application Protocol (SDAP) layer above the PDCP layer. An SDAP entity 514 may be established for the three types of bearers.

[0070] Since split SRBs are not supported in SRB3, the radio protocol architecture for SRB3 is simple and therefore will not be detailed herein.

[0071] Now, referring again to FIG. 3 , in order to discard the data unit at the RLC layer, one or more of the following operations may be performed at the terminal device 130: In some embodiments, the RLC entity of SRB3 may be re-established. For example, if an SCG suspension indication is received in an RRC message, the RRC layer may request re-establishment of the RLC entity of SRB3. In some embodiments, the RLC entity of the SCG bearer may be re-established. For example, if an SCG suspension indication is received in an RRC message, the RRC layer may request re-establishment of the RLC entity of the SCG bearer. In an EN-DC deployment, the NR RLC entity 422 may be re-established as shown in FIG. 4. In an NGEN-DC or NR-DC deployment, the SN RLC entity 522 may be re-established.

[0072] To re-establish an RLC entity (either an SRB3 or an SCG bearer), the terminal device 130 may discard all RLC service data units (SDUs), RLC SDU segments, and RLC protocol data units (PDUs) (if any) of the RLC entity. The terminal device 130 may stop and reset all timers maintained by the RLC entity and reset all state variables to their initial values.

[0073] Therefore, in such an embodiment, not only are the PDUs and SDUs of the RLC layer discarded, but also the timers and state variables are reset. Since the timers and state variables are reset during SCG suspension, it is possible to avoid resetting the timers and state variables during SCG resumption, which contributes to realizing an efficient SCG resumption.

[0074] In order to discard the data units of the PDCP layer, the terminal device 130 may perform one or more of the following operations. In some embodiments, the terminal device 130 may cause the PDCP entity of the SRB3 to discard the PDCP PDUs and PDCP SDUs of the PDCP entity. For example, the upper layer (e.g., the RRC layer) may trigger the PDCP entity of the SRB3 to perform the discarding of the PDCP SDUs. It should be understood that in the SRB, when the upper layer requests the discarding of the PDCP SDUs, the PDCP entity must discard all stored PDCP PDUs and PDCP SDUs. Therefore, by performing the discarding of the PDCP SDUs requested by the upper layer, both the PDCP PDUs and PDCP SDUs of the PDCP entity can be discarded.

[0075] In such an embodiment, the operation at the PDCP layer differs from that at the RLC layer. At the PDCP layer, buffered data units are discarded without re-establishment of a PDCP entity. The PDCP layer provides encryption and decryption functionality. If a PDCP entity is re-established, new keys for encryption and decryption are required when the SCG is resumed. Thus, in an embodiment that does not re-establish a PDCP entity, the efficiency of SCG suspension can be improved. Also, new keys do not need to be prepared when the SCG is resumed, which can improve the efficiency of SCG resumption.

[0076] In some embodiments, the terminal device 130 may cause the PDCP entity of the SCG bearer to discard the PDCP PDUs and PDCP SDUs of the PDCP entity. For example, a higher layer (e.g., the RRC layer) may indicate to the PDCP entity of the SCG bearer to discard all stored PDCP PDUs and PDCP SDUs. In an EN-DC deployment, the NR PDCP entity 423 shown in FIG. 4 may discard all PDCP PDUs and PDCP SDUs stored therein. In an NGEN-DC or NR-DC deployment, the NR PDCP entity 523 may discard all PDCP PDUs and PDCP SDUs stored therein.

[0077] Furthermore, in some embodiments, upon receiving the SCG suspension indication, the terminal device 130 may reset the MAC entity of the SCG, which may be referred to as the "SCG MAC entity." For example, a higher layer, such as the RRC layer, may request a reset of the SCG MAC entity. If a reset of the SCG MAC entity is requested by a higher layer, the terminal device 130 may perform a series of operations, such as, but not limited to, stopping all timers, aborting ongoing Random Access Channel (RACH) procedures, flushing various buffers, canceling various trigger procedures, resetting various counters, etc.

[0078] If an SCG suspension indication is received at a higher layer (e.g., the RRC layer), the higher layer may indicate to the SCG MAC entity of the SCG suspension. The terminal device 130 may further suspend transmissions in the SCG, including data transmissions and signaling. For example, the terminal device 130 may suspend SCG transmissions of all SRBs and DRBs.

[0079] In the above exemplary embodiment, the procedure of SCG suspension or deactivation is described. As a specific example without any limitation to the scope of the present disclosure, upon receiving the SCG suspension indication, the terminal device 130 may perform one or more of the following: resetting the SCG MAC entity, instructing the SCG MAC entity of SCG suspension, suspending SCG transmission of all SRBs and DRBs, re-establishing the RLC entity of SRB3, triggering the PDCP entity of SRB3 to perform SDU discard, instructing the PDCP entity of the SCG bearer to discard buffered PDUs and SDUs, and re-establishing the RLC entity of the SCG bearer. Example process for SCG reopening

[0080] SCG restart may be triggered or initiated by the MN or the SN. Figures 6A and 6B are signaling charts illustrating processes 600, 605 for triggering SCG restart according to some embodiments of the present disclosure. For discussion purposes, the processes 600, 605 are described with reference to Figure 1. The processes 600, 605 may involve terminal device 130, network device 110, and network device 120. In process 600 of Figure 6A, it is network device 110 acting as the MN that initiates SCG restart. In process 605 of Figure 6B, it is network device 120 acting as the SN that initiates SCG restart.

[0081] 6A, process 600 is discussed. The network device 110 decides to initiate an SCG restart (602). For example, if the network device 110 is unable to process traffic of the terminal device 130, the network device 110 may decide to initiate an SCG restart.

[0082] Next, network device 110 sends a request to network device 120 to resume or activate the SCG of network device 120 (604). This request may be referred to as an SCG resume request. Upon receiving the SCG resume request, network device 120 sends a response to the SCG resume request to network device 110 (606). This response may be referred to as an SCG resume response.

[0083] The network device 110 transmits (608) a message to the terminal device 130 indicating SCG resumption. This message may be referred to as an SCG resumption message. In some embodiments, upon receiving the SCG resumption message, the terminal device 130 may transmit (610) a response to the network device 110. As an example, the SCG resumption message may be an RRC Reconfiguration message and the response may be an RRC Reconfiguration Complete message. Other messages are also possible, such as messages specific to SCG resumption.

[0084] Upon receiving the response from the terminal device 130, the network device 110 sends (612) a message notifying the network device 120 of the SCG resumption. As an example, this message may be an SgNBReconfigurationComplete message.

[0085] Upon receiving the SCG resume message from the network device 110, the terminal device 130 executes a procedure to resume the SCG of the network device 120 (614). In this specification, this procedure may be referred to as an SCG resume procedure. The SCG resume procedure will be described below with reference to FIG. 7.

[0086] It should be understood that the order of operations shown in Figure 6A is for illustrative purposes only and does not imply any limitation on the scope of the present disclosure. For example, upon receiving an SCG resume message, terminal device 130 may perform an SCG resume procedure (614) and then send a response to network device 110 (610). Alternatively, upon receiving an SCG resume message, terminal device 130 may perform an SCG resume procedure (614) and simultaneously send a response to network device 110 (610).

[0087] Referring to Figure 6B, in Figure 6B, the network device 120 acting as a SN initiates an SCG restart. In process 605 of Figure 6B, the network device 120 determines (616) to initiate an SCG restart.

[0088] Network device 120 sends a request to network device 110 to resume the SCG (618). This request may also be referred to as an SCG resume request. Upon receiving the SCG resume request, network device 110 sends a confirmation for the SCG resume request to network device 120 (620). This may also be referred to as an SCG resume confirmation.

[0089] The network device 110 transmits an SCG resume message to the terminal device 130 (608). Operations with the same reference symbols as in Figure 6A are the same as those described with reference to Figure 6A, and therefore will not be described again here.

[0090] As can be seen from the processes 600, 605, whether the SCG resumption is initiated by the MN or the SN, it is the MN that indicates to the terminal device 130 to reactivate or activate the SCG associated with the SN. Figure 7 is a signaling chart illustrating a process 700 of SCG resumption according to some embodiments of the present disclosure. For discussion purposes, the process 700 will be described with reference to Figure 1. The process 700 may involve the terminal device 130, the network device 110 acting as the MN, and the network device 120 acting as the SN.

[0091] In process 700, network device 110 sends an instruction to end device 130 to resume or activate SCG 160 of network device 120 (702). For example, network device 110 may send the instruction if it determines to initiate an SCG resume (as shown in process 600). As another example, network device 110 may send the instruction if it receives an SCG resume request from network device 120 (as shown in process 605).

[0092] In this specification, this indication may also be referred to as a "second indication" or an "SCG restart indication." The SCG restart indication may be implemented by any suitable signaling. In some embodiments, the SCG restart indication may be included in an RRC message. In these embodiments, upon receiving the RRC message, the terminal device 130 may send a corresponding RRC message to the network device 110 in response (704). As an example, the network device 110 may send an RRC Reconfiguration message to indicate the SCG restart. An information element (IE) of the RRC Reconfiguration message may be used to indicate the SCG restart. In response, the terminal device 130 may send an RRC Reconfiguration Complete message to the network device 110 in response.

[0093] In such an embodiment, RRC signaling is used to transmit the SCG resume indication, thus reducing communication between different protocol layers in the terminal device 130 and contributing to efficient SCG resume.

[0094] Upon receiving the SCG restart instruction, the terminal device 130 executes an SCG restart procedure. Specifically, the terminal device 130 starts (706) a timer having an upper limit set by the network device 110. The timer, represented as "T3xx", is used to determine whether the SCG restart is successful.

[0095] In some embodiments, the upper limit value "t3xx" of timer T3xx may be indicated to terminal device 130 together with the SCG restart instruction. When the SCG restart instruction is included in the RRC message, the RRC message may further comprise an IE indicating the upper limit value t3xx. In some embodiments, the upper limit value t3xx of timer T3xx may be indicated to terminal device 130 separately from the SCG restart instruction. For example, the upper limit value t3xx may be a pre-set or pre-defined value.

[0096] The timers T3xx may be timers dedicated to the SCG resume indication. Alternatively or additionally, the timers T3xx may reuse existing timers, such as timer T304 for reconfiguration with synchronization, timer T319 for RRC resume request, etc. Further details of the timers T3xx are described below with reference to Table 1.

[0097] Continuing to refer to Figure 7. Upon receiving the SCG resume instruction, the terminal device 130 initiates a random access (RA) procedure in the PSCell 160-1, i.e., the primary cell of the SCG (708). For example, the terminal device 130 may transmit a random access preamble in the PSCell 160-1 to the network device 120.

[0098] In some embodiments, the RA procedure may be based on contention-free random access (CFRA). For example, the network device 120 may transmit information about the resources of the CFRA to the network device 110 in the SCG resume response (as described with reference to FIG. 6A) or in the SCG resume request (as described with reference to FIG. 6B). The network device 110 may include the information about the resources in the SCG resume indication, or may transmit the information about the resources together with the SCG resume indication to the terminal device 130. The terminal device 130 may transmit a random access preamble in the PSCell 160-1 using the resources determined from the SCG resume indication. In such an embodiment, the efficiency of the SCG resume may be improved by allocating dedicated resources for CFRA.

[0099] Also, upon receiving the SCG restart instruction, the terminal device 130 may further resume SCG transmission of all SRBs and DRBs and resume the SCG 160. For example, when the SCG restart instruction is received in a higher layer (e.g., an RRC layer), the higher layer may indicate to a lower layer (e.g., a MAC layer) that the SCG 160 is to be resumed.

[0100] Continuing with the process 700, if the random access procedure is successful, the terminal device 130 may stop the timer T3xx. For example, if a random access response is received from the network device 120, the terminal device 130 may determine that the SCG restart is successful and may stop the timer T3xx.

[0101] If timer T3xx expires, the terminal device 130 may determine that the SCG resumption has failed (710). The terminal device 130 may send a message to the network device 110 indicating a failure to resumption or activation of the SCG 160 (712). A failure to resumption or activation of the SCG 160 may be referred to as an "SCG resumption failure."

[0102] Table 1 below shows attributes of timer T3xx that can be summarized from the above description. The start condition of timer T3xx is the reception of an SCG resume instruction, and the stop condition of timer T3xx is the successful completion of random access in the corresponding PSCell 160. Upon expiration of timer T3xx, the terminal device 130 may inform the network device about the SCG resume failure, for example by sending a message indicating SCG resume failure to the network device. It should be understood that if timer T3xx reuses timer T304 or T319, the attributes of Table 1 may be added to the reused timer. [Table 1]

[0103] An SCG restart failure may be indicated by a failure type specific to SCG restart. For example, a new failure type may be defined for SCG restart. Alternatively or additionally, other failure types defined for other procedures may be reused to indicate an SCG restart failure. For example, a failure type defined for reconfiguration involving SCG synchronization may be reused.

[0104] In some embodiments, the message indicating SCG restart failure may be an SCGfailureinformation message. Figures 8A and 8B are schematic diagrams illustrating example messages 800, 805 indicating SCG restart failure according to some embodiments of the present disclosure.

[0105] In some embodiments, an existing failure type may be reused to indicate an SCG restart failure. For example, as shown in FIG. 8A, the failure type 811 of "synchReconfigFailureSCG" in "failureType" IE 810 may be reused to indicate an SCG restart failure.

[0106] In some embodiments, a new failure type may be introduced to indicate an SCG resume failure. The new failure type may be added to an existing IE. As shown in FIG. 8A, a failure type 821 of "scg-ResumeFailure" may be added to an IE 820 of "failureTypeExt-r16". The failure type 821 of "scg-ResumeFailure" is a failure type specialized for SCG resume failure. Alternatively, a new IE including the new failure type may be added. As shown in FIG. 8B, an IE 830 of "failureTypeExt-r17" may be added to the SCGfailureinformation message, and the failure type 831 of "scg-ResumeFailure" may be a failure type specialized for SCG resume failure.

[0107] Continuing with reference to Fig. 7, when timer T3xx expires, the terminal device 130 may cancel the random access procedure for SCG resumption. The terminal device 130 may perform the SCG suspension procedure described above with reference to Fig. 3. For example, the terminal device 130 may suspend SCG transmissions of all SRBs and DRBs and reset the SCG MAC entity. Exemplary Methods

[0108] 9 illustrates a flow chart of an example method 900 according to some embodiments of the present disclosure. Method 900 may be implemented in terminal device 130 as illustrated in FIG. It should be understood that method 900 may include additional blocks not illustrated and / or omit some blocks illustrated, and the scope of the present disclosure is not limited in this respect. For purposes of discussion, method 900 will be described from the perspective of terminal device 130 with reference to FIG. 1.

[0109] In block 910, the terminal device 130 receives a first instruction to deactivate a cell group of the second network device 120 from the first network device 110. The first network device 110 is a master node serving the terminal device 130, and the second network device 120 is a secondary node serving the terminal device 130. In block 920, the terminal device 120 discards a data link layer data unit of the terminal device 130. The data unit is intended for transmission in the cell group.

[0110] In some embodiments, for a radio link control (RLC) layer of the terminal device 130, at least one RLC entity has been previously established, and discarding the data units includes: re-establishing a first RLC entity of a signaling radio bearer in the cell group and discarding protocol data units (PDUs) of the first RLC entity and service data units (SDUs) of the first RLC entity, and re-establishing a second RLC entity of a data radio bearer in the cell group and discarding PDUs of the second RLC entity and SDUs of the second RLC entity.

[0111] In some embodiments, at least one PDCP entity has been previously established for a packet data convergence protocol (PDCP) layer of the terminal device 130, and discarding the data units includes: causing a first PDCP entity of a signaling radio bearer in the cell group to discard a protocol data unit (PDU) of the first PDCP entity and a service data unit (SDU) of the first PDCP entity, and causing a second PDCP entity of a data radio bearer in the cell group to discard a PDU of the second PDCP entity and an SDU of the second PDCP entity.

[0112] In some embodiments, the method 900 further includes resetting a media access control (MAC) entity of the cell group, the MAC entity being established for a MAC layer of the terminal device 130, and suspending transmissions in the cell group.

[0113] In some embodiments, the first instruction is included in a radio resource control (RRC) reconfiguration message, and the method 900 further includes sending an RRC reconfiguration complete message to the first network device 110 in response to receiving the RRC reconfiguration message.

[0114] In some embodiments, the method 900 further includes receiving a second instruction from the first network device 110 to activate the cell group of the second network device 120, starting a timer having an upper limit value set by the first network device 110, and initiating a random access procedure in a primary cell of the cell group.

[0115] In some embodiments, the method 900 further includes stopping the timer in response to determining that the random access procedure was successful.

[0116] In some embodiments, initiating the random access procedure includes determining resources for the random access procedure from the second indication, and initiating the random access procedure by transmitting a random access request in the primary cell using the determined resources.

[0117] In some embodiments, the method 900 further includes, in accordance with determining that the timer has expired, sending a message to the first network device 110 indicating that activation of the cell group of the second network device 120 has failed.

[0118] In some embodiments, a message is defined for failure information regarding a cell group, where the failure is indicated by at least one of a failure type specific to activation of the cell group or a failure type defined for reconfiguration associated with synchronization of the cell group.

[0119] In some embodiments, the method 900 further includes, in accordance with determining that the timer has expired, resetting a media access control (MAC) entity of the cell group, the MAC entity being established for a MAC layer of the terminal device 130, and suspending transmissions in the cell group.

[0120] In some embodiments, the second instruction and the information regarding the upper limit value are included in a radio resource control (RRC) reconfiguration message, and the method 900 further includes sending an RRC reconfiguration complete message to the first network device 110 in response to receiving the RRC reconfiguration message.

[0121] 10 illustrates a flow chart of an example method 1000 according to some embodiments of the present disclosure. Method 1000 may be implemented in a terminal device 130 as illustrated in FIG. It should be understood that method 1000 may include additional blocks not illustrated and / or omit some blocks illustrated, and the scope of the present disclosure is not limited in this respect. For purposes of discussion, method 1000 will be described from the perspective of terminal device 130 with reference to FIG. 1.

[0122] In block 1010, the terminal device 130 receives an instruction to activate a cell group of the second network device 120 from the first network device 110. The first network device 110 is a master node serving the terminal device 130, and the second network device 120 is a secondary node serving the terminal device 130. In block 1020, the terminal device 130 starts a timer having an upper limit value set by the first network device. In block 1030, the terminal device 130 initiates a random access procedure in a primary cell of the cell group.

[0123] In some embodiments, the method 1000 further includes stopping the timer in accordance with determining that the random access procedure was successful.

[0124] In some embodiments, initiating the random access procedure includes determining resources for the random access procedure from the indication, and initiating the random access procedure by transmitting a random access request in the primary cell using the determined resources.

[0125] In some embodiments, the method 1000 further includes, in accordance with determining that the timer has expired, sending a message to the first network device 110 indicating that activation of the cell group of the second network device 120 has failed.

[0126] In some embodiments, a message is defined for failure information regarding a cell group, where the failure is indicated by at least one of a failure type specific to activation of the cell group or a failure type defined for reconfiguration associated with synchronization of the cell group.

[0127] In some embodiments, the method 1000 further includes, in accordance with determining that the timer has expired, resetting a media access control (MAC) entity of the cell group, the MAC entity being established for a MAC layer of the terminal device 130, and suspending transmissions in the cell group.

[0128] In some embodiments, the instruction and information regarding the upper limit are included in a radio resource control (RRC) reconfiguration message, and the method 900 further includes sending an RRC reconfiguration complete message to the first network device 110 in response to receiving the RRC reconfiguration message.

[0129] In some embodiments, a method is provided that may be implemented in a network device, such as network device 110 as shown in Figure 1. The method may include operations performed by network device 110 as described with reference to Figures 2A, 2B, 3, 6A, 6B, and 7.

[0130] In some embodiments, a method is provided that may be implemented in a network device, such as network device 120 as shown in Figure 1. The method may include operations performed by network device 120 as described with reference to Figures 2A, 2B, 6A, 6B, and 7. Exemplary Apparatus

[0131] 11 is a schematic block diagram of an apparatus 1100 suitable for implementing embodiments of the present disclosure. The apparatus 1100 may be considered as a further exemplary implementation of the terminal apparatus 130, the network apparatus 120, or the network apparatus 110 shown in FIG. 1. Thus, the apparatus 1100 may be implemented in, or at least as a part of, the terminal apparatus 130, the network apparatus 120, or the network apparatus 110.

[0132] As shown in the figure, the apparatus 1100 comprises a processor 1110, a memory 1120 coupled to the processor 1110, a suitable transmitter (TX) and receiver (RX) 1140 coupled to the processor 1110, and a communication interface coupled to the TX / RX 1140. The memory 1110 stores at least a portion of a program 1130. The TX / RX 1140 is for bidirectional communication. The TX / RX 1140 has at least one antenna to facilitate communication, although in practice the access nodes discussed herein may have multiple antennas. The communication interface may represent any interface required for communication with other network elements, for example an X2 interface for bidirectional communication between eNBs, an S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and an eNB, an Un interface for communication between an eNB and a Relay Node (RN), or an Uu interface for communication between an eNB and a terminal device.

[0133] The program 1130 may be considered to include program instructions that, when executed by an associated processor 1110, enable the device 1100 to operate according to embodiments of the present disclosure, as discussed herein with reference to Figures 2A, 2B, 3, 6A, 6B, 7, 9, 10. The embodiments of the present disclosure may be implemented by computer software, hardware, or a combination of software and hardware executable by the processor 1110 of the device 1100. The processor 1110 may be configured to implement various embodiments of the present disclosure. The combination of the processor 1110 and the memory 1110 may also constitute a processing means 1150 suitable for implementing embodiments of the present disclosure.

[0134] The memory 1110 may be of any type suitable for the local technology network and may be implemented by any suitable data storage technology, including, but not limited to, computer-readable non-transitory storage media, semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed and removable memories, etc. Although only one memory 1110 is shown in the device 1100, multiple physically distinct memory modules may be installed in the device 1100. The processor 1110 may be of any type suitable for the local technology network and may include, but is not limited to, one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor configurations. The device 1100 may have multiple processors, for example application specific integrated circuit chips time-slaved to a clock synchronous with a master processor.

[0135] In general, various embodiments of the present disclosure may be implemented by hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented by hardware, and other aspects may be implemented by firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure have been shown and described as block diagrams, flow charts, or illustrated by some other pictorial representation, it will be understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented by, for example, but not limited to, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing device, or combinations thereof.

[0136] The present disclosure further provides at least one computer program product tangibly stored in a computer readable non-transitory storage medium. The computer program product includes computer executable instructions, such as instructions included in a program module. The instructions execute on a target real or virtual processor device to perform the process or method described above with reference to, for example, Figures 2A, 2B, 3, 6A, 6B, 7, 9, 10. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split among program modules as appropriate. The machine readable instructions of the program modules may be executed in local or distributed devices. In distributed devices, the program modules may be located in both local and remote storage media.

[0137] The program codes for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, a special purpose computer or other programmable data processing apparatus, and when the program codes are executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are performed. The program codes may run entirely on the machine, partially on the machine, as a separate software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0138] The above program code may be embodied on a machine-readable medium, which may be any tangible medium that contains or stores a program for use by or in conjunction with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Even more specific examples of machine-readable storage media include one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable-programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0139] It should be understood that although operations have been described in a particular order, it is not required that such operations be performed in the particular order or sequence shown, or that all of the operations shown be performed, in order to achieve desired results. In some situations, multitasking and parallel processing may be advantageous. Similarly, although the above discussion includes some specific implementation details, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to certain embodiments. Some features described in the context of individual embodiments may be implemented in combination in an embodiment. Conversely, various features described in the context of an embodiment may be implemented in multiple embodiments separately or in any suitable subcombination.

[0140] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure, as defined by the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for a terminal device, comprising: receiving a first instruction from the master node to deactivate a cell group associated with the secondary node; performing a deactivation procedure to trigger a Packet Data Convergence Protocol (PDCP) entity of a Signaling Radio Bearer 3 (SRB3) between the secondary node and the terminal device to perform Service Data Unit (SDU) discarding upon receiving the first indication to deactivate the cell group; If the deactivation procedure involves resetting a medium access control (MAC) of the cell group, stopping an ongoing random access procedure; method.

2. and re-establishing a first radio link control (RLC) entity for the SRB3. The method of claim 1.

3. The PDCP entity discards PDCP service data units (SDUs) and PDCP protocol data units (PDUs); The method according to claim 1 or 2.

4. and resetting a media access control (MAC) for the group of cells.

4. The method according to any one of claims 1 to 3.

5. the first indication is included in a radio resource control (RRC) reconfiguration message.

5. The method according to any one of claims 1 to 4.

6. The master node requests the secondary node to deactivate the cell group.

6. The method according to any one of claims 1 to 5.

7. the secondary node requests the master node to deactivate the cell group; 6. The method according to any one of claims 1 to 5.

8. Further, deactivating a primary cell of the cell group and a secondary cell of the cell group.

8. The method according to any one of claims 1 to 7.

9. and receiving a second message activating the cell group of the secondary node; initiate a random access procedure in a primary cell of the cell group associated with the secondary node; if the random access procedure is completed successfully, stopping a timer T304 that was started upon receiving the second message; 9. The method according to any one of claims 1 to 8.

10. the master node requests the secondary node to activate the cell group; 10. The method of claim 9.

11. the secondary node requests the master node to activate the cell group; 10. The method of claim 9.

12. means for receiving, from the master node, a first instruction to deactivate a cell group associated with the secondary node; means for performing a deactivation procedure to trigger a Packet Data Convergence Protocol (PDCP) entity of a Signaling Radio Bearer 3 (SRB3) between the secondary node and the secondary node to perform Service Data Unit (SDU) discard upon receiving the first indication to deactivate the cell group; means for stopping an ongoing random access procedure when a media access control (MAC) of the cell group is to be reset in the deactivation procedure; A terminal device comprising:

13. The terminal device re-establishes a first radio link control (RLC) entity for the SRB3. The terminal device according to claim 12.

14. The PDCP entity discards PDCP service data units (SDUs) and PDCP protocol data units (PDUs); A terminal device according to claim 12 or 13.

15. The terminal device resets a medium access control (MAC) for the cell group. A terminal device according to any one of claims 12 to 14.

16. the first indication is included in a radio resource control (RRC) reconfiguration message. A terminal device according to any one of claims 12 to 15.

17. the secondary node requests the master node to deactivate the cell group; A terminal device according to any one of claims 12 to 16.

18. The master node requests the secondary node to deactivate the cell group. A terminal device according to any one of claims 12 to 16.

19. The terminal device deactivates a primary cell of the cell group and a secondary cell of the cell group. A terminal device according to any one of claims 12 to 18.

20. the terminal device receives a second message activating the cell group of the secondary node; initiate a random access procedure in a primary cell of the cell group associated with the secondary node; if the random access procedure is completed successfully, stopping a timer T304 that was started upon receiving the second message; A terminal device according to any one of claims 12 to 19.

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