Master node, communication device, and communication method

Abstract

To provide a master base station configured not to continue packet duplication when a secondary cell group is deactivated, and a communication control method.SOLUTION: In a mobile communication system, a master base station 200-1 which is connected, together with a secondary base station 200-2, to a user device through a double connection scheme includes a PDCP entity 232 and a first RLC entity 233. The PDCP entity includes a control unit which outputs a PDCP PDU to the first RLC entity, and outputs a duplicated PDCP PDU to second RLC entities 243, 244 of the secondary base station. The PDCP entity deactivates the duplication of the PDCP PDU in the second RLC entities when a secondary cell group managed by the secondary base station is deactivated.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a master base station 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 equipment (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 equipment and provide additional radio resources to the user equipment.

[0004] In the dual connectivity method, the user equipment transmits and receives user data using the radio resources of the master node while transmitting and receiving user data using the radio resources of the secondary node. Thereby, the user equipment can improve throughput.

[0005] On the other hand, the power consumption of a user equipment 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, a technology for deactivating a secondary cell group (SCG) managed by a secondary node according to the situation has 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 has introduced packet duplication. Packet duplication is a technology in which a base station duplicates data (PDCP PDU (Packet Data Convergence Protocol Protocol Data Unit)) and transmits both the original data and the duplicated data to the user equipment.

[0009] Packet duplication can occur in two ways: either two data packets are transmitted from the same base station, or two data packets are transmitted from two different base stations (master node and secondary node). The former is sometimes called carrier aggregation (CA) duplication, and the latter is sometimes called dual-connection (DC) duplication.

[0010] User devices can perform processing such as using data received earlier and discarding data received later. Packet replication improves reliability and reduces latency, making it effective for URLLC (Ultra-Reliable and Low Latency Communications) services. [Prior art documents] [Non-patent literature]

[0011] [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 TS 38.300 V16.5.0 [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] However, 3GPP does not specify what should be done when the SCG becomes inactive in a base station that uses a dual connection method for packet duplication. Therefore, base stations may continue packet duplication even when the SCG becomes inactive.

[0013] Therefore, one embodiment aims to provide a master base station and a communication control method that prevents packet replication from continuing when the SCG becomes inactive. [Means for solving the problem]

[0014] A master base station according to one aspect of this disclosure is a master base station that connects to user equipment together with a secondary base station using a dual connection method. The master base station has a PDCP (Packet Data Convergence Protocol) entity and a first RLC (Radio Link Control) entity, and the PDCP entity has a control unit that outputs a PDCP PDU (Protocol Data Unit) to the first RLC entity and outputs a duplicated PDCP PDU to the second RLC entity of the secondary base station. When the secondary cell group managed by the secondary base station becomes inactive, the PDCP entity deactivates the duplication of the PDCU PDU to the second RLC entity.

[0015] A communication control method according to one aspect of this disclosure is a communication control method for a master base station that uses a dual connection method to connect to a user device together with a secondary base station and has a control unit including a PDCP (Packet Data Convergence Protocol) entity and a first RLC (Radio Link Control) entity. The communication control method includes the step of the PDCP entity outputting a PDCP PDU (Protocol Data Unit) to the first RLC entity and outputting a duplicated PDCP PDU to the second RLC entity of the secondary base station. The communication control method also includes the step of the PDCP entity deactivating the duplication of the PDCU PDU to the second RLC entity when the secondary cell group managed by the secondary base station becomes inactive. [Effects of the Invention]

[0016] According to one embodiment, a master base station and a communication control method can be provided that prevent packet replication from continuing when the SCG becomes inactive. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a diagram showing an example configuration of a mobile communication system according to the present disclosure. [Figure 2] Figure 2 is a diagram showing an example configuration of a protocol stack according to the embodiment of this disclosure. [Figure 3] Figure 3 is a diagram showing an example of the configuration of a protocol stack according to the present disclosure. [Figure 4] Figure 4 is a diagram showing an example configuration of a UE according to the present disclosure. [Figure 5] Figure 5 is a diagram showing an example of the configuration of a base station according to the present disclosure. [Figure 6] Figure 6 is a diagram showing an example of packet replication according to the embodiment of this 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 replication 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 this specification and the drawings, for elements that can be similarly described, duplicate descriptions may be omitted by attaching the same or similar labels.

[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. Also, the mobile communication system 1 may be a system of other generations after the 5G system (for example, the 6th generation).

[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] Note that "cell" is used as a term to indicate the smallest unit of a wireless communication area. "Cell" may also be used as a term to represent the 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.

[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 is sometimes referred to as the master gNB.

[0043] Secondary nodes do not have a control plane connection to the core network and provide additional wireless resources to the UE100. These secondary nodes are sometimes referred to as secondary gNBs.

[0044] Here, the master node and secondary node are logical entities. In the first embodiment, the master node corresponds to base station 200-1 and the secondary node corresponds to base station 200-2, and these 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, base station 200-1 may be referred to as master node 200-1 or master base station 200-1. Also, in the following, base station 200-2 may be referred to as secondary node 200-2 or secondary base station 200-2.

[0050] (1.4) Deactivation of SCG Next, we will explain how to deactivate SCG.

[0051] 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.

[0052] UE100 deactivates SCG by one of the following methods:

[0053] 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).

[0054] Method 2: UE100 deactivates the SCG when the timer for deactivating the SCG expires.

[0055] (1.5) Packet duplication Now, let's explain packet duplication.

[0056] When replication is configured for a radio bearer by RRC, at least one secondary RLC entity is added to handle the replicated PDCP PDU.

[0057] Figure 6 is a diagram showing an example of packet replication according to the embodiment of this disclosure. Details of Figure 6 will be described later. Here, an example of packet replication will be explained. In Figure 6, it is assumed that a duplex connection scheme is set up for two base stations 200-1 and 200-2. Base station 200-1 is the master base station, and base station 200-2 is the secondary base station.

[0058] In Figure 6, for example, if RLC entity 233 of master base station 200-1 is the primary RLC entity, then RLC entity 234 is added as a secondary RLC entity. Additionally, the two RLC entities 243 and 244 of secondary base station 200-2 are also added as secondary RLC entities.

[0059] In packet replication, the logical channel corresponding to primary RLC entity 233 becomes the primary logical channel, and the logical channels corresponding to each secondary RLC entity 234, 243, and 244 can become secondary logical channels.

[0060] In PDCP replication, the same PDCP PDU is output (submitted) to each RLC entity 233, 234, 243, and 244. Therefore, PDCP entity 232 can output the same data (PDCP PDU) to each RLC entity 233, 234, 243, and 244 through packet replication. In this case, PDCP entity 232 may output the original data to the primary RLC entity 233 and the replicated data to the secondary RLC entities 234, 243, and 244. However, the original PDCP PDU and the replicated PDCP PDU are not transmitted on the same carrier. Figure 6 shows an example where the original PDCP PDU is transmitted using CC (Component Carrier) #1, and the replicated PDCP PDU is transmitted using CC #2 to CC #4.

[0061] Furthermore, once data (or DRB: Data Bearer) replication is configured, dynamic control over PDCP replication becomes possible. Specifically, each of the secondary RLC entities 234, 243, and 244 can be activated or deactivated. This allows control over which secondary RLC entity is used to send the replication. Also, when replication is deactivated for a data bearer, all secondary RLC entities 234, 243, and 244 associated with that data bearer are deactivated. When secondary RLC entities 234, 243, and 244 are deactivated, PDCP entity 232 can instruct secondary RLC entities 234, 243, and 244 to discard all replicated PDCP PDUs.

[0062] It is also possible to configure a duplicate of the Signaling Radio Bearer (SRB). However, even if such a configuration is made, dynamic control cannot be performed on the duplicate. In the following explanation, the duplicate is described as a duplicate of the data (or PDCP PDU).

[0063] When replication is activated, at least one serving cell is activated for each logical channel associated with the activated RLC entities 233, 234, 243, and 244. That is, at least one serving cell is activated for the primary RLC entity 233, and at least one serving cell is activated for each secondary RLC entity 234, 243, and 244. On the other hand, if the deactivation of a secondary cell (S cell) results in no activated serving cells for a logical channel for the data bearer, replication is deactivated for the RLC entities 233, 234, 243, and 244 associated with that logical channel.

[0064] When the logical channels of data bearers configured through replication belong to the same MAC entities 235 and 245, it is called "CA replication." Conversely, when these logical channels belong to different MAC entities 235 and 245, it is called "DC replication." In the example in Figure 6, packet replication by two RLC entities 233 and 234 is CA replication because they belong to the same MAC entity 235. On the other hand, packet replication by primary RLC entity 233 and secondary RLC entities 243 and 244 is DC replication because they belong to different MAC entities 235 and 245. Below, we will mainly explain DC replication.

[0065] When RLC entities 233, 234, 243, and 244 become aware of the transmission of a PDCP PDU, PDCP entity 232 can instruct other RLC entities to discard that PDCP PDU.

[0066] (1.6) 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] (1.7) Example of base station configuration Figure 5 is a diagram showing an example configuration of base station 200. As shown in Figure 5, base station 200 has an antenna 201, a wireless communication unit 220, a control unit 230, a memory 240, and a network communication unit 250.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] The operation of the base station 200, as described later, may also be performed by the control unit 230.

[0077] 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.

[0078] The network communication unit 250 can communicate with other base stations. 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 the core network device 300 of 5GC30. The network communication unit 250 can communicate with the core network device 300 of 5GC30 using messages on the NG interface.

[0079] In the mobile communication system 1 configured as described above, in the first embodiment, the master base station 200-1 has the following configuration. That is, the master base station 200-1 of the first embodiment connects to the UE 100 together with the secondary base station 200-2 using a dual connection method. The master base station 200-1 has a PDCP entity 232 and a first RLC entity 233. The PDCP entity 232 has a control unit 230 that outputs a PDCP PDU to the first RLC entity 233 and outputs a duplicated PDCP PDU to the second RLC entities 243 and 244 of the secondary base station 200-2. Furthermore, when the secondary cell group (SCG) managed by the secondary base station 200-2 becomes inactive, the PDCP entity 232 deactivates the duplication of PDCU PDUs to the second RLC entities 243 and 244.

[0080] This allows the master base station 200-1 to also deactivate packet replication when the SCG becomes inactive. The details are explained below.

[0081] (2) An example of packet duplication Figure 6 shows an example of packet duplication. However, as mentioned above, it is assumed that the two base stations 200-1 and 200-2 and the UE100 are configured with a dual connection scheme. Master base station 200-1 manages the Master Cell Group (MCG), and secondary base station 200-2 manages the SCG.

[0082] As shown in Figure 6, the master base station 200-1 has an RRC entity 231 (or SDAP entity 231), a PDCP entity 232, RLC entities 233, 234, and a MAC entity 235. The secondary base station 200-2 has RLC entities 243, 244 and a MAC entity 245.

[0083] In addition, RLC entity 233 may be referred to as the first RLC entity, and RLC entity 243 (or RLC entity 244) may be referred to as the second RLC entity.

[0084] Furthermore, it is assumed that RLC entity 233 is set as the primary RLC entity, and the other RLC entities 234, 243, and 244 are set as secondary RLC entities.

[0085] As shown in Figure 6, PDCP entity 232 generates a PDCP PDU from a packet from the upper layer (SDAP layer). PDCP entity 232 performs packet duplication. PDCP entity 232 outputs the original PDCP PDU to RLC entity 233 (first RLC entity). PDCP entity 232 also outputs the duplicated PDCP PDU to RLC entity 234 and RLC entities 243 and 244 (second RLC entities) of secondary base station 200-2. PDCP entity 232 may also output the duplicated PDCP PDU to each RLC entity 233, 234, 243, and 244. PDCP entity 232 may also use the Xn interface to output (transmit) the duplicated PDCP PDU to RLC entities 243 and 244.

[0086] Each RLC entity 233, 234, 243, and 244 performs segmentation processing on each PDCP PDU to generate an RLC PDU. Each RLC entity 233, 234, 243, and 244 outputs the generated RLC PDU to MAC entities 235 and 245.

[0087] Each MAC entity 235 and 245 performs padding and other processing to generate a MAC PDU. Each MAC entity 235 and 245 outputs the generated MAC PDU to the PHY layer. The PHY layer generates a radio signal from the MAC PDU and transmits the generated radio signal to the UE100. In the example in Figure 6, the master base station 200-1 transmits the data output from RLC entity 233 using CC#1 and the data output from RLC entity 234 using CC#2. The secondary base station 200-2 transmits the data output from RLC entity 243 using CC#3 and the data output from RLC entity 244 using CC#4. The example in Figure 6 shows an example where data transmission is performed using four carriers.

[0088] (3) Example of operation Figure 7 is a diagram illustrating an example of operation according to the embodiment of this disclosure. It is assumed that a dual connection scheme is set for base stations 200-1, 200-2 and UE100 before the start of processing in Figure 7. Furthermore, each process shown in Figure 7 is described as being performed by the network. In this case, the network includes NG-RAN20. Therefore, for example, the master base station 200-1 may perform each process. The network may also include 5GC30. Therefore, for example, the core network device 300 may perform each process.

[0089] In step S10, the network starts processing.

[0090] In step S11, the network configures packet replication. For example, the master base station 200-1 configures packet replication by sending a predetermined message (e.g., a CG-Config Info message) to the secondary base station 200-2. Also, for example, the master base station 200-1 configures packet replication for the UE100 by sending a predetermined message (e.g., an RRC Reconfiguration message) to the UE100. As a result, each RLC entity 233, 234, 243, and 244 is activated. RLC entity 233 becomes the primary RLC entity, and the other RLC entities 234, 243, and 244 become secondary RLC entities. At least one serving cell is activated for the primary RLC entity 233, and at least one serving cell is also activated for each of the secondary RLC entities 234, 243, and 244.

[0091] In step S12, the SCG becomes inactive. The network (for example, RRC entity 231 of master base station 200-1) may decide to deactivate the SCG. Alternatively, the network (for example, RRC entity 231 of master base station 200-1) may detect that the SCG is inactive by receiving a message from secondary base station 200-2 indicating that the SCG has become inactive. RRC entity 231 of master base station 200-1 outputs a notification to PDCP entity 232 indicating that the SCG has become inactive. PDCP entity 232 can understand that the SCG has become inactive from this notification.

[0092] In step S13, the network deactivates packet replication to an RLC entity (e.g., secondary RLC entities 234, 243, 244) if all serving cells belonging to that RLC entity become inactive. Specifically, PDCP entity 232 deactivates packet replication to the second RLC entities 243, 244 for each logical channel associated with the first RLC entity 233 and the second RLC entities 243, 244 if the serving cells activated by packet replication cease to exist due to the SCG's inactive state. This allows the network to prevent continued packet replication.

[0093] In step S14, the network terminates the series of processes.

[0094] Figure 8 is a diagram illustrating an example of operation according to the specifications. As shown in Figure 8(X), in DC replication, when the SCG is deactivated and there are no more activated serving cells for the logical channel of the data bearer, the network (or NG-RAN20) deactivates packet replication for the RLC entities associated with that logical channel.

[0095] (4) Variations In the embodiment described above, an example was given in which duplicate packets are transmitted using four carriers. For example, as shown in Figure 9, duplicate packets may be transmitted using two carriers. In the example in Figure 9, RLC entity 233 is the primary RLC entity, and RLC entity 243 is the secondary RLC entity. In this case as well, the network (e.g., PDCP entity 232) deactivates packet duplication when the SCG managed by the secondary base station 200-2 becomes inactive and all serving cells belonging to the RLC entity (e.g., secondary RLC entity 243) become inactive. This makes it possible for the network to not continue packet duplication.

[0096] [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.

[0097] 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.

[0098] 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).

[0099] 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]

[0100] 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: Secondary base station 201: Antenna 220: Wireless Communication Department 230: Control Unit 231: RRC / SDAP Entity 232: PDCP Entity 233,234: RLC entities 235: MAC Entity 243,244: RLC entities 245: MAC Entity 240: Memory 250: Network Communications Department

Claims

1. A dual connection method is used, with a secondary node (200-2) and a master node (200-1) connected to the communication device (100), The system includes a PDCP (Packet Data Convergence Protocol) entity and a first RLC (Radio Link Control) entity, wherein the PDCP entity has a control unit (230) that outputs a PDCP PDU (Protocol Data Unit) to the first RLC entity and outputs a duplicated PDCP PDU to the second RLC entity of the secondary node (200-2), The system includes a transmitting unit that transmits to the communication device (100) information that sets up the deactivation of a secondary cell group, including a primary secondary cell (PScell), associated with the secondary node (200-2), and a radio resource control (RRC) message that includes the setting up the replication of the PDCP PDU. Based on the information that sets the deactivation of the secondary cell group including the PScell, the control unit deactivates the secondary cell group including the PScell ​​that has been activated for the logical channel of the data bearer. When the PDCP entity deactivates the secondary cell group including the PScell, it deactivates the replication of the PDCP PDU to the second RLC entity associated with the logical channel of the data bearer. If the PDCP PDU copy to the second RLC entity is deactivated, the second RLC entity is deactivated. Master node (200-1).

2. A communication method for a secondary node (200-2) and a master node (200-1) connected to a communication device (100), using a dual connection method, It has a PDCP (Packet Data Convergence Protocol) entity and a first RLC (Radio Link Control) entity, The PDCP entity outputs a PDCP PDU (Protocol Data Unit) to the first RLC entity, and outputs the duplicated PDCP PDU to the second RLC entity of the secondary node (200-2). A radio resource control (RRC) message is sent to the communication device (100) including information to deactivate a secondary cell group, including a primary secondary cell (PScell), associated with the secondary node (200-2), and the setting for replication of the PDCP PDU. The PDCP entity deactivates the secondary cell group including the PScell ​​that has been activated for the logical channel of the data bearer, based on the information that sets the deactivation of the secondary cell group including the PScell. When the PDCP entity deactivates the secondary cell group including the PScell, it deactivates the replication of the PDCP PDU to the second RLC entity associated with the logical channel of the data bearer. If the PDCP PDU copy to the second RLC entity is deactivated, the second RLC entity is deactivated. Communication method.

3. A communication device (100) that connects to a master node (200-1) and a secondary node (200-2) using a dual connection method, A control unit (130) that controls the reception of a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a replicated PDCP PDU, The system includes a communication unit (120) that receives a radio resource control (RRC) message, which includes information for setting the deactivation of a secondary cell group, including a primary secondary cell (PScell), associated with the secondary node (200-2), and the setting for the replication of the PDCP PDU. Based on the information that sets the deactivation of the secondary cell group including the PScell, the control unit (130) deactivates the secondary cell group including the PScell ​​that has been activated for the logical channel of the data bearer. When the secondary cell group including the PScell ​​is deactivated, the RLC entity associated with the logical channel of the data bearer receives the deactivated PDCP PDU. Communication device (100).

4. The aforementioned secondary cell group includes secondary cells The master node according to claim 1.

5. The aforementioned secondary cell group includes secondary cells The communication method according to claim 2.

6. The aforementioned secondary cell group includes secondary cells The communication device according to claim 3.

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