Communication device and communication control method

Abstract

The present invention provides a user device and a communication control method that suppress the increase in power consumption of the user device. [Solution] In a user device (100) connected to a master base station (200-1) and a first secondary base station (200-2) using a dual connection method, the device includes a control unit (130) that activates the primary secondary cell (PSCell) when the primary secondary cell (PSCell) is changed from the first secondary base station (200-2) to the second secondary base station (200-3) while the secondary cell group managed by the first secondary base station (200-2) is in an inactive state, and a wireless communication unit (120) that executes a random access procedure to the second secondary base station (200-3) in response to the activation of the primary secondary cell.

Description

Technical Field

[0001] The present invention relates to a user device used in a mobile communication system and a communication control method.

Background Art

[0002] In 3GPP (Third Generation Partnership Project), which is a standardization project for mobile communication systems, a dual connectivity (DC) method has been introduced.

[0003] In the dual connectivity method, among a plurality of base stations, only one base station (hereinafter sometimes referred to as a "master base station" or a "master node") establishes an RRC (Radio Resource Control) connection with a user device (UE (User Equipment)). On the other hand, among a plurality of base stations, other base stations other than the master base station (hereinafter sometimes referred to as a "secondary base station" or a "secondary node") do not establish an RRC connection with the user device and provide additional radio resources to the user device.

[0004] In the dual connectivity method, the user device uses the radio resources of the master node to transmit and receive user data, and uses the radio resources of the secondary node to transmit and receive user data. Thereby, the user device can improve throughput.

[0005] On the other hand, the power consumption of a user device performing wireless communication by the dual connectivity method is higher than that in the case of performing wireless communication with one base station.

[0006] Therefore, in 3GPP, technologies for deactivating a secondary cell group (SCG) managed by a secondary node have been studied.

[0007] Regarding the deactivation of the SCG, the following are some of the agreements reached in 3GPP: only the master node can generate RRC messages regarding the activation or deactivation of the SCG, and user devices can instruct the master node that they wish to deactivate the SCG.

[0008] On the other hand, 3GPP specifies PSCel Change (hereinafter sometimes referred to as "PS cell change"). A PS cell is the primary cell of the SCG managed by a secondary node. A PS cell change allows the secondary node managing the SCG to be switched from the source secondary node to the target secondary node. For example, if a user device moves away from the source secondary node and closer to the target secondary node, a PS cell change can be performed to switch the secondary node managing the SCG to the target secondary node.

[0009] 3GPP is discussing how PS cell changes should be performed when the SCG is deactivated. For example, 3GPP has proposed the following: When the SCG is inactive during a PS cell change, it is proposed that the user device should not perform random access to the target PS cell. Also, when the target SCG is configured to be inactive, it is proposed that the user device should perform random access to the target PS cell during the PS cell change. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] 3GPP TS 37.340 V16.5.0 [Non-Patent Document 2] 3GPP contribution: R2-2104315 [Non-Patent Document 3] 3GPP contribution: R2-2103977 [Non-Patent Document 4] 3GPP contribution: R2-2106023 [Non-Patent Document 5] 3GPP contribution: R2-2105829 [Overview of the project] [Problems that the invention aims to solve]

[0011] However, regarding PS cell changes when the SCG is deactivated, the user device may not be able to perform random access procedures on the target secondary node because the SCG is inactive.

[0012] If a user device is unable to perform a random access procedure to a target secondary node, it may attempt to reconnect to that secondary node. When a user device attempts to reconnect, its power consumption increases compared to when it does not.

[0013] Therefore, one embodiment aims to provide a user device and a communication control method that suppress an increase in the power consumption of the user device. [Means for solving the problem]

[0014] A user device according to one aspect of this disclosure is connected to a master base station and a first secondary base station using a dual connection method. The user device includes a control unit that activates a primary secondary cell (PSCell) when the primary secondary cell (PSCell) is changed from the first secondary base station to the second secondary base station while the secondary cell group managed by the first secondary base station is inactive, and a wireless communication unit that executes a random access procedure to the second secondary base station in response to the activation of the primary secondary cell.

[0015] A communication control method according to an aspect of the present disclosure is a communication control method in a user equipment that is connected to a master base station and a first secondary base station and has a control unit and a wireless communication unit, using a dual connection method. The communication control method includes a step in which the control unit activates the primary secondary cell when the primary secondary cell (PSCell) is changed from the first secondary base station to a second secondary base station while the secondary cell group managed by the first secondary base station is in an inactive state. Further, the communication control method includes a step in which the wireless communication unit executes a random access procedure for the second secondary base station in response to activating the primary secondary cell.

Advantages of the Invention

[0016] According to one aspect, it is possible to provide a master base station and a communication control method that enable packet duplication to be deactivated when the SCG becomes inactive.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a diagram showing a configuration example of a mobile communication system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a configuration example of a protocol stack according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram showing a configuration example of a protocol stack according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram showing a configuration example of a UE according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram showing a configuration example of a base station according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram showing an example of packet duplication according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram showing an operation example according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram showing an operation example in terms of specifications according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing an example of packet duplication according to an embodiment of the present disclosure.

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the present specification and drawings, for elements that can be similarly described, duplicate descriptions may be omitted by attaching the same or similar reference numerals.

[0019] [First Embodiment] (1.1) Configuration Example of Mobile Communication System FIG. 1 is a configuration example of a mobile communication system 1 according to an embodiment of the present disclosure. The mobile communication system 1 is, for example, a 3GPP 5G (5th Generation) system. The mobile communication system 1 may include a mixture of an LTE system and a 5G system. Also, the mobile communication system 1 may include a mixture of a 5G system and another generation (for example, the 6th generation). The mobile communication system 1 may include a system compliant with a standard other than 3GPP.

[0020] As shown in FIG. 1, the mobile communication system 1 includes a radio access network (hereinafter, may be referred to as "NG-RAN" (Next Generation Radio Access Network)) 20, a core network (hereinafter, may be referred to as "5GC" (5G Core Network)) 30, and a user equipment (hereinafter, may be referred to as "UE" (User Equipment)) 100.

[0021] NG-RAN 20 includes a base station (gNB) 200 which is a node of the radio access network.

[0022] Base station 200 is a wireless communication device that communicates wirelessly with UE100. Base station 200 manages one or more cells. Within its own cell, base station 200 communicates wirelessly with UE100 with which it has established an RRC connection. Base station 200 has wireless resource management functions, user data (hereinafter sometimes referred to as "data") routing functions, and measurement and control functions for mobility control and scheduling.

[0023] The term "cell" is used to indicate the smallest unit of a wireless communication area. It may also be used to represent a function or resource that performs wireless communication with the UE100. One cell belongs to one carrier frequency. In Figure 1, base station 200-1 manages cell C1, and base station 200-2 manages cell C2. Note that NG-RAN20 may include base station 200-3. In this case, base station 200-3's cell C3 has a cell range that includes the overlapping range of cells C1 and C2. The UE100 may be located within the overlapping range of cells C1, C2, and C3.

[0024] 5GC30 includes a core network device 300.

[0025] The core network device 300 includes a device corresponding to the control plane. In this case, the core network device 300 can perform various mobility controls on the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The core network device 300 may also be an AMF (Access Management Function) or an MME (Mobility Management Entity).

[0026] Furthermore, the core network device 300 includes a device corresponding to the user plane. In this case, the core network device 300 controls the data transfer of the UE 100. The core network device 300 may be a UPF (User Plane Function) or an S-GW (Serving Gateway).

[0027] As shown in Figure 1, each base station 200-1 and 200-2 are interconnected with the 5GC30 via an interface called the NG interface. In addition, each base station 200-1 and 200-2 are interconnected via an interface called the Xn interface.

[0028] UE100 is a mobile wireless communication device, such as a smartphone, tablet, personal computer, communication module, or communication card. UE100 may also be a vehicle (e.g., car, train, etc.) or a device installed in a vehicle. Furthermore, UE100 may be a transport vehicle (e.g., ship, airplane, etc.) or a device installed in a transport vehicle. Additionally, UE100 may be a sensor or a device installed in a sensor. Note that UE100 may also be used as an alternative name for mobile station, mobile terminal, mobile device, mobile unit, subscriber station, subscriber terminal, subscriber equipment, remote station, remote terminal, remote device, or remote unit.

[0029] In Figure 1, UE100 is shown as being present in both cell C1, managed by base station 200-1, and cell C2, managed by base station 200-2.

[0030] (1.2) Example of protocol stack configuration Figure 2 is a diagram showing an example of the configuration of a protocol stack according to the embodiment of this disclosure. Figure 2 shows an example of the configuration of a protocol stack relating to a control plane.

[0031] As shown in Figure 2, the control plane protocols, including the PHY (Physical) layer, MAC (Media Access Control) layer, RLC (Radio Ink Control) layer, PDCP (Packet Data Convergence Protocol) layer, and RRC layer, are included in the UE100 and base station 200. Furthermore, the NAS layer is included in the UE100 and core network equipment 300.

[0032] The PHY layer performs coding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of base station 200 via a physical channel.

[0033] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of base station 200 via the transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the transport format (transport block size, modulation / encoding scheme) and allocated resource blocks for the uplink and downlinks.

[0034] The RLC layer transmits data to the receiving RLC layer by utilizing the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of base station 200 via a logical channel.

[0035] The PDCP layer performs header compression / decompression, and encryption / decryption. Data and control information are transmitted between the UE100's PDCP layer and the base station 200's PDCP layer via a wireless bearer.

[0036] The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of base station 200. When there is an RRC connection with base station 200, UE100 is in the RRC connected state. When there is no RRC connection with base station 200, UE100 is in the RRC idle state.

[0037] The NAS layer handles session management and mobility management, among other things. NAS signaling is transmitted between the NAS layer of UE100 and the NAS layer of the core network device 300.

[0038] Figure 3 is a diagram showing an example of the configuration of a protocol stack according to the embodiment of this disclosure. Figure 3 shows an example of the configuration of a protocol stack relating to the user plane.

[0039] As shown in Figure 3, the user plane protocols included in UE100 and base station 200 are the PHY layer, MAC layer, RLC layer, PDCP layer, and SDAP (Service Data Protocol) layer.

[0040] The SDAP layer maps QoS (Quality of Service) flows to data radio bearers and assigns QoS flow IDs (Identification) to both the uplink (UL) and downlink (DL).

[0041] (1.3) Dual connection method The UE100 can utilize resources provided by two different nodes connected via a non-ideal backhaul. In this scenario, one node becomes the master node (MN) managing a master cell group (hereinafter sometimes referred to as "MCG"). The other node becomes the secondary node (SN) managing a secondary cell group (hereinafter sometimes referred to as "SCG"). The master node and secondary node are connected via a network interface (Xn interface). At least the master node is connected to the core network.

[0042] The master node provides a single control plane to the core network (e.g., 5GC30). The master node may also be referred to as a master eNB (evolved Node B), master ng-eNB (new generation -eNB), or master gNB.

[0043] Secondary nodes do not have control plane connectivity to the core network and provide additional wireless resources to the UE100. Secondary nodes may be referred to as en-gNB, secondary ng-eNB, or secondary gNB.

[0044] Here, the master node and secondary node are logical entities. In this embodiment, the master node corresponds to base station 200-1 and the secondary node corresponds to base station 200-2, and will be described below.

[0045] An MCG is a cell group of serving cells associated with a master node. An MCG has a primary cell (Sp cell or P cell) and optionally one or more secondary cells (S cells).

[0046] An SCG is a group of serving cells associated with a secondary node. An SCG has a primary cell (Sp cell or PS cell) and optionally one or more secondary cells (S cells). The Sp cell is the primary cell in both the MCG and the SCG.

[0047] The UE100 can connect to a master node that manages the MCG, and simultaneously connect to a secondary node that manages the SCG. In this case, the UE100 connects to each node simultaneously and performs wireless communication.

[0048] The dual connection configuration is achieved when the master node sends a predetermined message (for example, an SN Addition Request message) to the secondary node, and then the master node sends an RRC message (for example, an RRC Reconfiguration message) to the UE100.

[0049] In the following text, base station 200-1 may be referred to as master node 200-1 or master base station 200-1. Similarly, base station 200-2 may be referred to as secondary node 200-2 or secondary base station 200-2. Furthermore, base station 200-2 may be referred to as source secondary node 200-2, and base station 200-3 may be referred to as target secondary node 200-3.

[0050] In a dual connection configuration, the PS cell of the SCG may be changed. A PS cell change may reset the MAC entity and re-establish the RLC entity configured for the SCG. A PS cell change may also trigger a secondary node change procedure. In the first embodiment, a PS cell change triggers a change procedure that changes the secondary node from source secondary node 200-2 to target secondary node 200-3. Details are explained in the operation example.

[0051] (1.4) Deactivation of SCG Next, we will explain how to deactivate SCG.

[0052] 3GPP is considering deactivating the SCG to reduce the power consumption of the UE100. When the SCG is deactivated, the UE100 will deactivate all cells (PSCells and SCells) belonging to the SCG. The UE100 will not report CSI (Channel Status Information) for cells belonging to a deactivated SCG, nor will it monitor PDCCH. In addition, the UE100 will not transmit RACH (Random Access Channel), SRS (Sounding Reference Signal), UL-SCH (UL-Shared Channel), etc. to those cells. This will reduce the power consumption of the UE100.

[0053] UE100 deactivates SCG by one of the following methods:

[0054] Method 1: UE100 deactivates the SCG in response to receiving an instruction from the master node (base station 200-1) to deactivate the SCG. This instruction is transmitted via RRC layer signaling (RRC message), MAC layer signaling (MAC CE), or PHY layer signaling (PDCCH).

[0055] Method 2: UE100 deactivates the SCG when the timer for deactivating the SCG expires.

[0056] (1.5) Example of UE configuration Figure 4 is a diagram showing an example configuration of UE100. As shown in Figure 4, UE100 has an antenna 101, a wireless communication unit 120, a control unit 130, and a memory 140.

[0057] Antenna 101 receives radio signals transmitted from base station 200 and outputs the received radio signals to wireless communication unit 120. Antenna 101 also transmits radio signals output from wireless communication unit 120 to base station 200.

[0058] The wireless communication unit 120, under the control of the control unit 130, performs wireless communication with the base station 200 via the antenna 101. For example, the wireless communication unit 120 converts the wireless signal output from the antenna 101 into a baseband signal (received signal) (downconverts it) and outputs the converted baseband signal to the control unit 130. Alternatively, for example, the wireless communication unit 120 converts the baseband signal (transmitted signal) output from the control unit 130 into a wireless signal (upconverts it) and outputs the converted wireless signal to the antenna 101.

[0059] The control unit 130 performs various controls on the UE 100. For example, the control unit 130 controls wireless communication with the base station 200 or with other UEs via the wireless communication unit 120. The control unit 130 may perform various operations by processing the received signal output from the wireless communication unit 120. The control unit 130 may also perform various operations and output a transmission signal to the wireless communication unit 120. The operation of the UE 100, which will be described later, may also be performed by the control unit 130.

[0060] Memory 140 stores various information under the control of the control unit 130. Memory 140 may also function as the working memory of the control unit 130. Alternatively, memory 140 may store a program. In this case, the control unit 130 reads the program from memory 140 and executes it to realize the operation of the UE100. Memory 140 may be ROM (Read Only Memory) or RAM (Random Access Memory), etc.

[0061] (1.6) Example of base station configuration Figure 5 shows an example configuration of base station 200. The base station 200 shown in Figure 5 may be any of base stations 200-1 to 200-3.

[0062] As shown in Figure 5, the base station 200 includes an antenna 201, a wireless communication unit 220, a control unit 230, a memory 240, and a network communication unit 250.

[0063] Antenna 201 receives the radio signal transmitted from UE100 and outputs the received radio signal to the wireless communication unit 220. Antenna 201 also transmits the radio signal output from the wireless communication unit 220 to UE100.

[0064] The wireless communication unit 220, under the control of the control unit 230, performs wireless communication with the UE 100 via the antenna 201. For example, the wireless communication unit 220 converts the wireless signal output from the antenna 201 into a baseband signal (received signal) (downconverts it) and outputs the converted baseband signal to the control unit 230. Alternatively, for example, the wireless communication unit 220 converts the baseband signal (transmitted signal) output from the control unit 230 into a baseband signal (transmitted signal) (upconverts it) and outputs the converted wireless signal to the antenna 201.

[0065] The control unit 230 performs various controls at the base station 200. The control unit 230 controls wireless communication with the UE 100, for example, via the wireless communication unit 220. The control unit 230 may perform various operations by processing the received signal output from the wireless communication unit 220. Alternatively, the control unit 230 may perform various operations and output a transmission signal to the wireless communication unit 220.

[0066] Furthermore, the control unit 230 controls communication with the core network device 300 or other base stations via the network communication unit 250. The control unit 230 receives messages and other information transmitted from the core network device 300 or other base stations via the network communication unit 250 and performs various operations. In addition, the control unit 230 performs various operations and instructs the network communication unit 250 to generate and transmit messages, thereby enabling the network communication unit 250 to transmit various messages to the core network device 300 or other base stations.

[0067] The operation of the base station 200, as described later, may also be performed by the control unit 230.

[0068] Memory 240 stores various information under the control of the control unit 230. Memory 240 may also function as the working memory of the control unit 230. Alternatively, memory 240 may store programs. In this case, the control unit 230 reads and executes the program from memory 240 to realize the operation of the base station 200. Memory 240 may be ROM (Read Only Memory) or RAM (Random Access Memory), etc.

[0069] The network communication unit 250 can communicate with other base stations or with each node of 5GC30. The network communication unit 250 can communicate with other base stations using messages on the Xn interface. In addition, the network communication unit 250 can communicate with each node of 5GC30 using messages on the NG interface.

[0070] In the mobile communication system 1 configured in this way, in the first embodiment, the UE100 has the following configuration. That is, the UE100 of the first embodiment is connected to the master base station 200-1 and to the first secondary base station (for example, secondary node 200-2) using a dual connection method. The UE100 has a control unit 130 that activates the PS cell (or PSCell) when the PS cell is changed from the first secondary base station to the second secondary base station (for example, secondary node 200-3) while the secondary cell group managed by the first secondary base station is inactive. The UE100 also has a wireless communication unit 120 that executes a random access procedure to the second secondary base station in response to the activation of the PS cell.

[0071] Thus, when the SCG is inactive, the UE100 activates the PS cell when the secondary node is changed from the first secondary node to the second secondary node. This allows the UE100 to perform a random access procedure to the second secondary node which has the PS cell. As a result, the UE100 does not need to perform a reconnection process to the second secondary node, which helps to suppress the increase in power consumption of the UE100.

[0072] (2) Example of operation Figure 6 is a diagram illustrating an example of operation according to the embodiment of this disclosure.

[0073] It should be assumed that a dual connection scheme is set up between UE100 and base stations 200-1 and 200-2 before the process shown in Figure 6 begins.

[0074] In the following, master base station 200-1 may be referred to as master node (hereinafter sometimes referred to as "MN") 200-1. Secondary base station 200-2 may be referred to as secondary node (hereinafter sometimes referred to as "SN") 200-2. Furthermore, base station 200-2 may be referred to as source SN200-2, and base station 200-3 may be referred to as target SN200-3.

[0075] As shown in Figure 6, in step S10, the control unit 130 of UE100 detects that the SCG of SN200-2 has been deactivated. For example, the control unit 230 of MN200-1 generates an RRC message indicating that the SCG of SN200-2 is inactive and transmits it to UE100 via the wireless communication unit 220. The control unit 130 of UE100 detects that the SCG of SN200-2 has become inactive by receiving the RRC message via the wireless communication unit 120.

[0076] In step S11, the control unit 130 of UE100 sends a Measurement Report to MN200-1. For example, UE100 sends a Measurement Report when certain conditions are met, such as when the received signal strength from source SN200-2 falls below a threshold and the received signal strength from target SN200-3 rises above a threshold.

[0077] In step S12, the control unit 230 of MN200-1 sends an SN Addition Request message to the target SN200-3 in response to the receipt of the Measurement Report. The SN Addition Request message is a message requesting the addition of an SN.

[0078] In step S13, the control unit 230 of target SN200-3 sends an SN Addition Request ACK message to MN200-1 in response to the receipt of the SN Addition Request message. The SN Addition Request ACK message is a message indicating permission to add to the SN in response to the SN Addition Request message.

[0079] In step S14, the control unit 230 of MN200-1 sends an SN Release Request message to the source SN200-2 in response to receiving an SN Addition Request ACK. The SN Release Request message is a message requesting that the SN be released.

[0080] In step S15, the control unit 230 of source SN200-2 sends an SN Release Request ACK to MN200-1 in response to the receipt of the SN Release Request message. The SN Release Request ACK message is a message that indicates permission for release from the SN in response to the SN Release Request message.

[0081] In step S16, the control unit 230 of MN200-1 sends an RRC Reconfiguration message to UE100 in response to the receipt of the SN Release Request ACK message. The RRC Reconfiguration message may include reconfigurationWithSync. reconfigurationWithSync may be an information element that instructs UE100 to activate the PS cell (in the subsequent step S18) or deactivate the PS cell (in the subsequent step S20). Alternatively, reconfigurationWithSync may include an information element that instructs UE100 to activate the PS cell (in the subsequent step S18) or deactivate the PS cell (in the subsequent step S20).

[0082] In step S17, the control unit 130 of UE100 performs the reconfiguration according to the RRC Reconfiguration message and then sends an RRC Reconfiguration Complete message to MN200-1.

[0083] In step S18, the control unit 130 of UE100 activates the PS cell. That is, the control unit 130 of UE100 activates a PS cell that has become inactive due to the deactivation of the SCG. Specifically, when the SCG managed by the first secondary base station 200-2 is inactive (step S10), the control unit 130 activates the PS cell when the PS cell is changed from the first secondary base station 200-2 to the second secondary base station 200-3. The control unit 130 may activate the PS cell in response to instructions from MN200-1 (e.g., reconfigurationWithSync), or it may autonomously activate the PS cell without receiving instructions from MN200-1.

[0084] In step S19, the control unit 130 of UE100 performs a random access procedure. In this case, the control unit 130 may perform the random access procedure on the PS cell of target SN200-3. By performing the random access procedure on target SN200-3, the control unit 130 completes the connection to target SN200-3.

[0085] In step S20, the control unit 130 of the UE100 deactivates the activated PS cell. The control unit 130 may deactivate the PS cell in response to instructions from the MN200-1 (e.g., reconfigurationWithSync), or it may autonomously activate the PS cell without receiving instructions from the MN200-1.

[0086] Figures 7 to 9 are diagrams illustrating example operations according to the embodiments of this disclosure. Of these, Figure 7 shows example operations for EN-DC and NGEN-DC. EN-DC is a dual connection method between eNB (evolved Node B) and en-gNB, where the MN (eNB) is connected to the EPC. NGEN-DC is a dual connection method between ng-eNB and gNB, where the MN (ng-eNB) is connected to the 5GC. EN-DC and NGEN-DC are sometimes collectively referred to as (NG)EN-DC.

[0087] Specifically, as shown in Figure 7, this represents an example where a dual connection method is configured using (NG)EN-DC, an RRC Reconfiguration message is received, and the RRC Reconfiguration message includes reconfigurationWithSync. Then, as shown in (X) of Figure 7, when the SCG is deactivated, UE100 activates the Sp cell. (X) of Figure 7 corresponds, for example, to step S18 in Figure 6.

[0088] Figure 8 shows an example of operation in the case of NR-DC. NR-DC is a dual connection method between gNBs. Also, as shown in Figure 8, it shows an example where an RRC Reconfiguration message is received and the RRC Reconfiguration message includes reconfigurationWithSync. Then, as shown in Figure 8(X), when the SCG is deactivated, UE100 activates the PS cell. Figure 8(X) also corresponds to step S18 in Figure 6, for example.

[0089] Figure 9 shows an example of operation corresponding to S20 in Figure 6. As shown in (X) of Figure 9, when the SCG is deactivated (e.g., S10 in Figure 6) and the Sp cell is activated (e.g., S18 in Figure 6), the Sp cell is deactivated. For UE100, the Sp cell that was activated to perform the random access procedure is returned to its original inactive state.

[0090] [Other embodiments] The above-described examples of actions can be performed not only individually and independently, but also in combination as appropriate. Furthermore, for example, the steps in the process described herein do not necessarily have to be executed chronologically in the order shown in the flowchart or sequence diagram. For example, the steps in the process may be executed in a different order than that shown in the flowchart or sequence diagram, or they may be executed in parallel. Also, some of the steps in the process may be deleted, or further steps may be added to the process.

[0091] Furthermore, methods including the operation of one or more components of the apparatus described herein may be provided, and programs for causing a computer to perform the operation of the above components may be provided. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM. An example of such a recording medium is the memory 140,240 described above.

[0092] Alternatively, the circuits that perform each process carried out by the UE100 or base station 200 may be integrated, and at least a portion of the UE100 or base station 200 may be configured as a semiconductor integrated circuit (chipset, SoC).

[0093] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the gist of the work. Furthermore, it is possible to combine all or part of each embodiment without contradiction. [Explanation of Symbols]

[0094] 1: Mobile communication systems 20: Wireless access network 30: Core Network 100: User Equipment (UE) 101: Antenna 120: Wireless Communication Department 130: Control Unit 140: Memory 200:Base station 200-1: Master base station 200-2, 200-3: Secondary base stations 201: Antenna 220: Wireless Communication Department 230: Control Unit 240: Memory 250: Network Communications Department

Claims

1. A communication device connected to a master node associated with a master cell group, and to a secondary node associated with a secondary cell group including a primary secondary cell, A receiving unit that receives a first RRC (Radio Resource Control) Reconfiguration message including an instruction to deactivate the secondary cell group, The system includes a control unit that performs deactivation of the secondary cell group based on the receipt of the first RRCReconfiguration message which includes an instruction to deactivate the secondary cell group, If the secondary cell group is deactivated, the control unit activates the primary secondary cell and performs a random access procedure in the primary secondary cell based on the receipt of a second RRCReconfiguration message which includes the information element reconfigurationWithSync and does not include an instruction to deactivate the secondary cell group. Communication device.

2. A communication control method in a communication device connected to a master node associated with a master cell group and a secondary node associated with a secondary cell group including a primary secondary cell, The steps include receiving a first RRC (Radio Resource Control) Reconfiguration message that includes an instruction to deactivate the secondary cell group, The steps include: performing deactivation of the secondary cell group based on the receipt of the first RRCReconfiguration message which includes an instruction to deactivate the secondary cell group; The procedure includes the steps of activating the primary secondary cell and performing a random access procedure in the primary secondary cell, based on the receipt of a second RRCReconfiguration message which includes the information element reconfigurationWithSync and does not include an instruction to deactivate the secondary cell group, when the secondary cell group is deactivated. Communication control method.

Images