Communication control method, user equipment, processor, base station, program product, and mobile communication system

Abstract

A communication control method, a user equipment, a processor, a base station, a program product, and a mobile communication system are provided. The user equipment is provided with a receiving unit for receiving a data packet belonging to an MBS service via a PTM radio bearer, and a control unit. A receiving unit receives, from a base station, configuration information for configuring an association between a PTP data path for receiving a data packet belonging to an MBS service and a PTM radio bearer. The control unit associates the PTP data path with the PTM radio bearer based on the configuration information.

Description

[0001] This application is a divisional application of the invention patent application with application date of May 27, 2021, application number 202180060231.X, and invention name “Communication Control Method and User Equipment”. Technical Field

[0002] The invention relates to a communication control method and user equipment in a mobile communication system. Background Art

[0003] 3GPP (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, has been conducting standardization of NR (New Radio) positioned as a fifth generation (5G) radio access technology.

[0004] The current NR specification does not define a mechanism for MBS (Multicast and Broadcast Service) services. 3GPP has started discussions on the introduction of MBS services (NPL 1).

[0005] Reference List

[0006] Non-patent literature

[0007] NPL 1: 3GPP contribution “RP-193248” Summary of the invention

[0008] In a first aspect, a communication control method includes: receiving, by a user equipment, a data packet belonging to an MBS (Multicast and Broadcast Service) service via a PTM (Point-to-Multipoint) radio bearer; receiving, by the user equipment from a base station, configuration information for configuring an association between the PTM radio bearer and a PTP (Point-to-Point) data path for receiving data packets belonging to the MBS service; and associating, by the user equipment, the PTP data path with the PTM radio bearer based on the configuration information.

[0009] In a second aspect, a user equipment includes: a receiver configured to receive data packets belonging to an MBS (Multicast and Broadcast Service) service via a PTM (Point-to-Multipoint) radio bearer; and a controller. The receiver receives configuration information for configuring an association between the PTM radio bearer and a PTP (Point-to-Point) data path for receiving data packets belonging to the MBS service from a base station. The controller associates the PTP data path with the PTM radio bearer based on the configuration information. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a diagram showing a configuration of a mobile communication system according to an embodiment.

[0011] Figure 2 is a diagram showing the configuration of UE 100 .

[0012] Figure 3 is a diagram showing the configuration of the base station 200 .

[0013] Figure 4 is a diagram showing a configuration of a protocol stack of a radio interface of a user plane.

[0014] Figure 5 is a diagram showing a configuration of a protocol stack of a radio interface of a control plane.

[0015] Figure 6 is a diagram showing an example of DC.

[0016] Figure 7 is a diagram showing an example for receiving MBS service.

[0017] Figure 8 is a diagram showing a sequence of basic operations according to the embodiment.

[0018] Fig. 9 is a diagram showing association between a PTP radio bearer and a PTM radio bearer according to an embodiment.

[0019] Fig.10 is a diagram showing the association between a PTP logical channel and a PTM radio bearer according to an embodiment.

[0020] Fig.11 is a diagram showing the operation in operation mode 1 according to the embodiment.

[0021] Fig.12 is a diagram showing the operation in Operation Mode 2 according to the embodiment.

[0022] Fig.13 : is a diagram showing the operation in the operation mode 3 according to the embodiment. DETAILED DESCRIPTION

[0023] From a service continuity perspective, delivery of MBS services to user equipment may desirably switch between PTM (point-to-multipoint) transmission and PTP (point-to-point) transmission in an appropriate manner.

[0024] An object of the present disclosure is to control the switching of the delivery of MBS services between PTM transmission and PTP transmission in an appropriate manner.

[0025] A mobile communication system according to an embodiment will be described with reference to the accompanying drawings. In the description of the drawings, the same and / or similar parts are denoted by the same and / or similar reference numerals.

[0026] Mobile communication system

[0027] First, the configuration of the mobile communication system according to the embodiment will be described. Although the mobile communication system according to the embodiment is a 5G system of 3GPP, LTE may be at least partially applied to the mobile communication system.

[0028] Figure 1 is a diagram showing a configuration of a mobile communication system according to an embodiment.

[0029] like Figure 1 As shown, the mobile communication system includes a user equipment (UE) 100 , a 5G radio access network (NG-RAN (Next Generation Radio Access Network)) 10 , and a 5G core network (5GC) 20 .

[0030] UE 100 is a mobile device. UE 100 may be any device as long as UE 100 is used by a user. Examples of UE 100 include a mobile phone terminal (including a smart phone), a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided on a sensor, a vehicle or a device provided on a vehicle (vehicle UE), and / or an aircraft or a device provided on an aircraft (aviation UE).

[0031] The NG-RAN 10 includes a base station (referred to as a "gNB" in the 5G system) 200. The gNB 200 may also be referred to as an NG-RAN node. The gNBs 200 are interconnected via an Xn interface which is an interface between base stations. Each gNB 200 manages one or more cells. The gNB 200 performs wireless communication with the UE 100, which has established a connection to the cell of the gNB 200. The gNB 200 has a radio resource management (RRM) function, a function of routing user data (hereinafter referred to as "data"), and / or a measurement control function for mobility control and scheduling, etc. "Cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource used to perform wireless communication with the UE 100. One cell belongs to one carrier frequency.

[0032] Note that the gNB can be connected to the Evolved Packet Core (EPC) which is the core network of LTE, or the base station of LTE can be connected to the 5GC. The base station of LTE and the gNB can be connected via an inter-base station interface.

[0033] The 5GC 20 includes an access and mobility management function (AMF) and a user plane function (UPF) 300. The AMF performs various types of mobility control and the like for the UE 100. The AMF manages information of the area in which the UE 100 exists by communicating with the UE 100 using non-access stratum (NAS) signaling. The UPF controls data transmission. The AMF and the UPF are connected to the gNB 200 via an NG interface which is an interface between a base station and a core network.

[0034] Figure 2 is a diagram showing the configuration of UE 100 (User Equipment).

[0035] like Figure 2 As shown, UE 100 includes a receiver 110 , a transmitter 120 , and a controller 130 .

[0036] The receiver 110 performs various types of reception under the control of the controller 130 . The receiver 110 includes an antenna and a receiving device. The receiving device converts a radio signal received through the antenna into a baseband signal (received signal) and outputs the resulting signal to the controller 130 .

[0037] The transmitter 120 performs various types of transmission under the control of the controller 130. The transmitter 120 includes an antenna and a transmission device. The transmission device converts a baseband signal (transmission signal) output by the controller 130 into a radio signal and transmits the resulting signal through the antenna.

[0038] The controller 130 performs various types of control in the UE 100. The controller 130 includes at least one processor and at least one memory electrically connected to the processor. The memory stores programs to be executed by the processor and information to be processed by the processor. The processor may include a baseband processor and a central processing unit (CPU). The baseband processor performs modulation and demodulation, encoding and decoding of baseband signals, etc. The CPU executes the program stored in the memory to perform various types of processing.

[0039] Figure 3 is a diagram showing the configuration of gNB 200 (base station).

[0040] like Figure 3 As shown, gNB 200 includes a transmitter 210, a receiver 220, a controller 230 and a backhaul communicator 240.

[0041] The transmitter 210 performs various types of transmission under the control of the controller 230. The transmitter 210 includes an antenna and a transmission device. The transmission device converts a baseband signal (transmission signal) output by the controller 230 into a radio signal and transmits the resulting signal through the antenna.

[0042] The receiver 220 performs various types of reception under the control of the controller 230. The receiver 220 includes an antenna and a receiving device. The receiving device converts a radio signal received through the antenna into a baseband signal (received signal) and outputs the resulting signal to the controller 230.

[0043] The controller 230 performs various types of control in the gNB 200. The controller 230 includes at least one processor and at least one memory electrically connected to the processor. The memory stores a program to be executed by the processor and information to be used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, encoding and decoding of a baseband signal, etc. The CPU executes a program stored in the memory to perform various types of processing.

[0044] The backhaul communicator 240 is connected to the neighboring base station via the inter-base station interface. The backhaul communicator 240 is connected to the AMF / UPF 300 via the interface between the base station and the core network. Note that the gNB may include a central unit (CU) and a distributed unit (DU) (ie, the functions are divided), and the two units may be connected via the F1 interface.

[0045] Figure 4 is a diagram showing a configuration of a protocol stack of a radio interface of a user plane processing data.

[0046] like Figure 4 As shown, the radio interface protocol of the user plane includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0047] The PHY layer provides a transport channel to the MAC layer. The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping.

[0048] The MAC layer performs priority control of data, a retransmission process (HARQ process) by hybrid ARQ (HARQ), a random access process, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the transport format (transport block size, modulation and coding scheme (MCS)) in uplink and downlink, and resource blocks to be allocated to the UE 100. The MAC layer provides a logical channel to the RLC layer. The MAC entity resides in the MAC layer.

[0049] The RLC layer sends data to the RLC layer of the receiving side by using the functions of the MAC layer and the PHY layer. The RLC layer performs a retransmission process (ARQ process) through ARQ. The RLC layer provides an RLC channel to the PDCP layer. The RLC entity resides in the RLC layer.

[0050] The PDCP layer performs data transmission, PDCP SN maintenance, header compression and decompression, and encryption and decryption. The PDCP layer provides radio bearers to the SDAP layer. The PDCP entity resides in the PDCP layer. One PDCP entity carries data for one radio bearer.

[0051] The SDAP layer performs mapping between QoS flows and radio bearers. QoS flows are units for which QoS control is performed by the core network. Note that when the RAN is connected to the EPC, the SDAP layer does not need to be provided. The SDAP entity resides in the SDAP layer.

[0052] Figure 5 is a diagram showing a configuration of a protocol stack of a radio interface in a control plane that processes signaling (control signals).

[0053] like Figure 5 As shown, the protocol stack of the radio interface in the control plane includes a radio resource control (RRC) layer and a non-access stratum (NAS) layer, instead of Figure 4 The SDAP layer is shown.

[0054] RRC signaling for various configurations is transmitted between the RRC layer of the UE 100 and the RRC layer of the gNB 200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, reestablishment, and release of radio bearers. When a connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200 exists, the UE 100 is in the RRC connected state. When a connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200 does not exist, the UE 100 is in the RRC idle state. When the RRC connection is suspended, the UE 100 is in the RRC inactive state.

[0055] The NAS layer higher than the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300.

[0056] Note that the UE 100 has an application layer and the like in addition to the protocol of the radio interface.

[0057] Dual Connection

[0058] The outline of dual connectivity (DC) will be described. In the following, DC including NR access is mainly assumed. Such DC may be referred to as multi-RAT DC (MR-DC) or multi-connectivity. Figure 6 is a diagram showing an example of DC.

[0059] like Figure 6 As shown, in DC, a UE 100 including multiple transceivers is configured to utilize resources (time resources and frequency resources) provided by two different nodes (two different base stations). One base station provides NR access, and the other base station provides E-UTRA (LTE) or NR access. Figure 6 In the example shown, base station 200A can be an eNB or a gNB, and base station 200B can be an eNB or a gNB.

[0060] One base station 200A is used as a master node and the other base station 200B is used as a secondary node. The master node is a radio access node that provides a control plane connection to the core network. The master node may be referred to as a master base station. The secondary node is a radio access node that does not have a control plane connection to the core network. The secondary node may be referred to as a secondary base station.

[0061] The primary node is connected to the secondary node via a network interface (inter-base station interface), and at least the primary node is connected to the core network. Figure 6 An example in which the inter-base station interface is an Xn interface is shown; however, the inter-base station interface may be an X2 interface.

[0062] A serving cell group that is a cell of a master node and configured for the UE 100 is referred to as a master cell group (MCG). On the other hand, a serving cell group that is a cell of a secondary node and configured for the UE 100 is referred to as a secondary cell group (SCG). The UE 100 includes a MAC entity corresponding to the MCG (MCG MAC) and a MAC entity corresponding to the SCG (SCG MAC).

[0063] Overview of MBS service reception

[0064] An overview of MBS service reception will be described. The UE 100 may receive the MBS service in an RRC connected state, or may receive the MBS service in an RRC idle state or an RRC inactive state.

[0065] Figure 7 is a diagram showing an example of receiving an MBS service. Figure 7As shown, in step S1, UE 100 obtains MBS basic information from 5GC 20 via gNB 200. MBS basic information may be referred to as User Service Description (USD). MBS basic information includes: for each MBS service, MBS identification information for identifying the MBS service and the frequency at which the MBS service is provided. MBS identification information may be referred to as Temporary Mobile Group Identity (TMGI).

[0066] In step S2, UE 100 receives MBS SIB from gNB 200. MBS SIB includes information (scheduling information) required to acquire a PTM control channel for MBS.

[0067] In step S3, the UE 100 receives MBS control information from the gNB 200 via the PTM control channel for MBS based on the MBS SIB. The MBS control information includes information required to configure a PTM data channel for MBS in the cell that transmits the MBS control information. The PTM data channel is a PTM logical channel for data transmission. The PTM logical channel may be a multicast logical channel or may be a broadcast logical channel.

[0068] In step S4, UE 100 establishes a PTM radio bearer with gNB 200 based on the MBS control information, and receives data packets (MBS data packets) belonging to the MBS service in which UE 100 is interested via the PTM radio bearer.

[0069] Communication control method

[0070] A communication control method according to the embodiment will be described.

[0071] (1) Basic operations

[0072] Figure 8 is a diagram showing a sequence of basic operations according to the embodiment.

[0073] like Figure 8 As shown, in step S11, UE 100 receives association configuration information for configuring an association of a PTM radio bearer with a PTP data path from gNB 200 to receive data belonging to an MBS service (MBS data). The PTP data path is a PTP radio bearer or a PTP logical channel. Note that the PTP data path may be an IP flow. An IP flow is a flow of a series of packets from a specific IP address to a specific IP address. The PTP radio bearer may be a unicast radio bearer. The PTP logical channel may be a unicast logical channel.

[0074] In step S12, the UE 100 associates the PTP data path with the PTM radio bearer based on the association configuration information. This allows the delivery of MBS services to the UE 100 to be switched between PTM and PTP.

[0075] A case where a PTP radio bearer is associated with a PTM radio bearer (ie, a case where the above-mentioned “PTP data path” is a PTP radio bearer) is described. Fig. 9 is a diagram showing the association between a PTP radio bearer and a PTM radio bearer.

[0076] like Fig. 9 As shown, UE 100 associates the PTP radio bearer (RB #2) with the PTM radio bearer (RB #1) based on the association configuration information. This association configuration information includes information for configuring the association between the PTP radio bearer and the PTM radio bearer (hereinafter, referred to as "PTP radio bearer configuration information").

[0077] The PTP radio bearer configuration information includes a bearer identifier of the PTP radio bearer (bearer identifier of RB #2) and PDCP configuration information of a PDCP entity for configuring the PTP radio bearer. The PTP radio bearer configuration information may also include a bearer identifier of a PTM radio bearer to be associated with the PTP radio bearer. When only one PTM radio bearer is established in the UE 100, the PTP radio bearer configuration information may not include the bearer identifier of the PTM radio bearer, but may include the bearer identifier of the PTP radio bearer and information indicating that the PTP radio bearer is a bearer for MBS service reception (e.g., "for MBS" = "true").

[0078] Here, the PTP radio bearer to be associated with the PTM radio bearer may be a radio bearer already established in the UE 100 , or may be a radio bearer newly established by the UE 100 .

[0079] Once the UE 100 receives the PTP radio bearer configuration information, the UE 100 determines whether the bearer identifier of the PTP radio bearer included in the PTP radio bearer configuration information is already stored in the UE 100. When the bearer identifier is already stored in the UE 100 (i.e., when the UE 100 has already established the PTP radio bearer identifying the bearer identifier), the UE 100 reconfigures the PDCP entity of the PTP radio bearer identified by the bearer identifier based on the PDCP configuration information. When the bearer identifier is not stored in the UE 100, the UE 100 newly establishes a PDCP entity based on the PDCP configuration information, and newly establishes a PTP radio bearer corresponding to the PDCP entity.

[0080] The PTP radio bearer configuration information may include SDAP configuration information for configuring an SDAP entity corresponding to the PTM radio bearer. The UE 100 configures the SDAP entity corresponding to the PTM radio bearer based on the SDAP configuration information.

[0081] The PTP radio bearer configuration information may include an identifier of an MBS service to which the data packets transmitted on the PTP radio bearer belong.

[0082] like Fig. 9 As shown, UE 100 includes a higher layer entity (MBS entity) residing in a layer higher than the PDCP layer, which manages the MBS service. The PDCP entity or the SDAP entity delivers data packets received via the PTP radio bearer to the MBS entity. The MBS entity may be included in the SDAP entity (ie, the SDAP entity manages the MBS service).

[0083] The case where a PTP logical channel is associated with a PTM radio bearer (ie, the case where the PTP data path is a PTP logical channel) is described. Fig.10 is a diagram showing the association between PTP logical channels and PTM radio bearers.

[0084] like Fig.10 As shown, UE 100 associates the PTP logical channel with the PTM radio bearer (RB #1) based on the association configuration information. This association configuration information includes information for configuring the association between the PTP logical channel and the PTM radio bearer (hereinafter, referred to as "PTP logical channel configuration information").

[0085] The PTP logical channel configuration information includes a bearer identifier of a PTM radio bearer and a channel identifier of a PTP logical channel to be associated with the PTM radio bearer.

[0086] Once the UE 100 receives the PTP logical channel configuration information, the UE 100 determines whether the channel identifier included in the PTP radio bearer configuration information is already stored in the UE 100. When the channel identifier is already stored in the UE 100, the UE 100 reconfigures the RLC entity corresponding to the PTP logical channel identified by the channel identifier. When the channel identifier is not stored in the UE 100, the UE 100 newly establishes the RLC entity and newly establishes the PTP logical channel corresponding to the RLC entity.

[0087] Therefore, the UE 100 associates the PTP logical channel identified by the channel identifier with the PDCP entity of the PTM radio bearer. Fig.10As shown, in this case, the PDCP entity of the PTM radio bearer is associated with one PTM logical channel and one PTP logical channel. The RLC entity corresponding to the PTP logical channel transmits data packets received via the PTP logical channel to the PDCP entity of the PTM radio bearer.

[0088] The UE 100 may enable or disable the above-mentioned PTP data path (PTP data path for the UE 100 to receive data belonging to the MBS service) in response to an instruction from the gNB 200. This allows the delivery of the MBS service to the UE 100 to be dynamically switched between PTM and PTP. Note that the UE 100 may enable or disable the PTM data path (PTM radio bearer or PTM logical channel) in response to an instruction from the gNB 200.

[0089] The above-mentioned association configuration information may include information for configuring the initial state (enabled state or disabled state) of the PTP data path configured with the association. Enabling the PTP data path includes starting reception via the PTP data path. Disabling the PTP data path includes stopping reception via the PTP data path. For example, once the UE 100 receives the association configuration information including information for configuring the initial state of the PTP data path as a disabled state, the UE 100 associates the PTP data path with the PTM radio bearer and disables the PTP data path. Thereafter, the UE 100 enables the PTP data path in response to an indication from the gNB 200, and starts receiving MBS data via the PTM data path. Note that the association configuration information may include information for configuring the initial state (enabled state or disabled state) of the PTM data path configured with the association.

[0090] When the PTP radio bearer is associated with the PTM radio bearer, the UE 100 may stop reception via the PTM radio bearer after activating the PTP radio bearer.

[0091] When a PTP logical channel is associated with a PTM radio bearer, the UE 100 may stop reception via the PTM logical channel associated with the PTM radio bearer after enabling the PTP logical channel.

[0092] The above-mentioned indication of enabling and / or indication of disabling is performed, for example, by a MAC CE (control element). The indication may include an identifier indicating the subject (PTP data path and / or PTM data path) to be enabled / disabled. Alternatively, the indication may include information (e.g., 1 bit) indicating enabling / disabling, and the information may be associated with the subject (PTP data path and / or PTM data path) to be enabled / disabled by the array.

[0093] When the UE 100 configured with the above-mentioned association is switched, the gNB 200 sends information indicating the association to another gNB 200 that manages the target cell to which the UE 100 is to be switched.

[0094] When DC is configured for UE 100, the PTP data path in the above association may be a data path using resources of the secondary node (base station 200B) (hereinafter, referred to as "SCG data path"). On the other hand, a PTM radio bearer is established between UE 100 and the primary node (base station 200A).

[0095] When the SCG data path is a PTP radio bearer, the PTP radio bearer is a radio bearer established between the UE 100 and the base station 200B. When the SCG data path is a PTP logical channel, the PTP logical channel is a logical channel corresponding to the SCG MAC entity of the UE 100.

[0096] UE 100 receives the association configuration information from base station 200A and configures the association. On the other hand, base station 200A transmits information indicating the association configured by the association configuration information to base station 200B.

[0097] (2) Operation mode 1

[0098] Operation mode 1 according to the embodiment assuming the above-mentioned basic operation is described. Operation mode 1 is an example in which the UE 100 transmits a sequence number corresponding to an MBS data packet that needs to be received in PTP transmission.

[0099] Fig.11 is a diagram showing operations in operation mode 1. In the initial state of this operation mode, UE 100 is in a state of establishing an RRC connection with gNB 200 (RRC connected state).

[0100] like Fig.11 As shown, in step S101, UE 100 receives MBS service from gNB 200 via PTM radio bearer.

[0101] In step S102, the UE 100 receives association configuration information from the gNB 200. Here, the association configuration information includes information for configuring the initial state of the PTM data path as a disabled state. The association configuration information may be sent in an RRC message (e.g., an RRCReconfiguration message).

[0102] In step S103, the UE 100 associates the PTP data path with the PTM radio bearer and disables the PTP data path.

[0103] In step S104, UE 100 measures a parameter indicating the communication quality between UE 100 and gNB 200 (communication quality on the PTM radio bearer) to determine whether the parameter satisfies a threshold condition.

[0104] The parameter indicating the communication quality corresponds to at least one selected from the group consisting of reference signal received power (RSRP), reference signal received quality (RSRQ), reference signal-to-interference plus noise power ratio (RS-SINR), throughput, error rate, the number of data packets failed to be received, and the duration of the reception failure (e.g., the number of milliseconds, the number of subframes, or the number of SFNs).

[0105] Here, the parameter indicating that the communication quality satisfies the threshold condition indicates that the communication quality is not good. When the parameter indicating the communication quality corresponds to at least one selected from the group consisting of RSRP, RSRQ, RS-SINR, and throughput, satisfying the threshold condition means that the parameter indicating the communication quality is equal to or less than the threshold. When the parameter indicating the communication quality corresponds to at least one selected from the group consisting of an error rate, the number of data packets failed to be received, and the duration of reception failure, satisfying the threshold condition means that the parameter indicating the communication quality is less than the threshold. The threshold of the threshold condition is configured by gNB 200 for UE 100.

[0106] When the parameter indicating the communication quality satisfies the threshold condition (step S104 : Yes), the UE 100 proceeds with the process to step S105 .

[0107] In step S105, the UE 100 transmits information indicating a sequence number corresponding to an MBS data packet that needs to be received in the PTP transmission scheme (hereinafter, "SN information") to the gNB 200. The SN information may be transmitted in an RRC message. The sequence number is any one of a PDCP sequence number, an RLC sequence number, and a new sequence number for MBS. For example, the new sequence number for MBS may be defined as a PDU (Packet Data Unit) header dedicated to MBS in an SDAP header.

[0108] The SN information may indicate a sequence number (e.g., SN #n) corresponding to the first MBS data packet that the UE 100 needs to receive in the PTP transmission scheme, or may indicate a range of sequence numbers (e.g., SN #n to SN #n+m) corresponding to multiple MBS data packets that the UE 100 needs to receive in the PTP transmission scheme.

[0109] The SN information may include identification information for identifying the MBS service to which the MBS data packet belongs. The SN information may include a bearer identifier of a PTM radio bearer. Therefore, when transmitting a plurality of MBS services, the gNB 200 may identify the MBS service requested by the UE 100 among the plurality of MBS services, and may send an MBS data packet corresponding to the MBS service to the UE 100.

[0110] In step S106, gNB 200 sends an indication to UE 100 to enable the PTP data path.

[0111] In step S107, UE 100 enables the PTP data path and starts receiving MBS data packets via the PTP data path. Here, when receiving SN information indicating a sequence number, gNB 200 sends the MBS data packet corresponding to the sequence number and subsequent MBS data packets to UE 100 via the PTP data path. When receiving SN information indicating a range of sequence numbers, gNB 200 sends a plurality of MBS data packets corresponding to the range of sequence numbers to UE 100 via the PTP data path. When the transmission of the plurality of MBS data packets is completed, gNB 200 may send an indication to UE 100 to disable the PTP data path.

[0112] In Operation Example 1, the process in step S104 may be omitted. In the case where the process in step S104 is omitted, when the UE 100 needs to receive the MBS data packet in the PTP, the UE 100 transmits the SN information.

[0113] (3) Operation mode 2

[0114] Operation mode 2 according to the embodiment will be described mainly focusing on the differences from operation mode 1. Fig.12 is a diagram showing an operation in operation mode 2. In the initial state of this operation mode, the state of UE 100 corresponds to any one of an RRC connected state, an RRC idle state, and an RRC inactive state.

[0115] like Fig.12 As shown, in step S201, UE 100 receives MBS service from gNB 200 via PTM radio bearer.

[0116] The process in step S202 is the same as and / or similar to the process in step S104 .

[0117] In step S203, UE 100 sends SN information to gNB 200. Here, when UE 100 is in RRC inactive state or RRC idle state, UE 100 can transition to RRC connected state and then send SN information to gNB 200. UE 100 can send SN information while performing an RRC connection establishment process for transitioning from RRC idle state to RRC connected state. For example, UE 100 includes and sends SN information in an RRCSetupRequest message. UE 100 can send SN information while performing an RRC connection recovery process for transitioning from RRC inactive state to RRC connected state. For example, UE 100 includes and sends SN information in an RRCResumeRequest message.

[0118] In step S204, the UE 100 receives association configuration information from the gNB 200. Here, the association configuration information includes information for configuring the initial state of the PTM data path to an enabled state. The association configuration information may be sent in an RRCReconfiguration message.

[0119] When the gNB 200 receives the RRCSetupRequest message including the SN information in step S203, the gNB 200 includes and sends the associated configuration information in the RRCSetup message in step S204. The RRCSetup message is a message for transitioning the UE 100 from the RRC idle state to the RRC connected state. In response to the reception of the RRCSetup message, the UE 100 transitions to the RRC connected state.

[0120] When gNB 200 receives the RRCResumeRequest message including the SN information in step S203, gNB 200 includes and transmits the associated configuration information in the RRCResume message in step S204. The RRCResume message is a message for transitioning UE 100 from the RRC inactive state to the RRC connected state. In response to the reception of the RRCResume message, UE 100 transitions to the RRC connected state.

[0121] In step S205 , the UE 100 associates the PTP data path with the PTM radio bearer and enables the PTP data path to start receiving MBS data packets via the PTP data path.

[0122] (4) Operation mode 3

[0123] Operation mode 3 according to the embodiment will be described mainly focusing on the differences from operation mode 1. Fig.13is a diagram showing an operation for operation mode 3. In the initial state of this operation mode, the state of UE 100 corresponds to any one of an RRC connected state, an RRC idle state, and an RRC inactive state.

[0124] In step S301, UE 100 receives MBS service from gNB 200 via PTM radio bearer.

[0125] The process in step S302 is the same and / or similar to the process in step S104. When the parameter indicating the communication quality satisfies the threshold condition (step S302: Yes), the UE 100 proceeds with the process to step S303. On the other hand, when the parameter indicating the communication quality does not satisfy the threshold condition (step S302: No), the UE 100 proceeds with the process to step S304.

[0126] In step S303, UE 100 sends SN information to gNB 200.

[0127] In step S304, the UE 100 applies transmission of negative acknowledgement (NACK) feedback. NACK feedback is feedback information for requesting retransmission of an MBS data packet via a PTM radio bearer. The NACK feedback may be information for requesting retransmission by a HARQ process (HARQ feedback), or may be information for requesting retransmission by an ARQ process (ARQ feedback). When failing to receive an MBS data packet transmitted via a PTM radio bearer, the UE 100 applying transmission of NACK feedback transmits NACK feedback corresponding to the MBS data packet to the gNB 200. When receiving the NACK feedback, the gNB 200 retransmits the data packet corresponding to the NACK feedback on the PTM radio bearer (PTM logical channel).

[0128] In this way, the UE 100 under the gNB 200 applies transmission of NACK feedback or switches to PTP transmission according to the communication quality. Therefore, frequent PTM retransmission caused by all UE 100 under the gNB 200 applying transmission of NACK feedback can be avoided.

[0129] Other embodiments

[0130] In the above embodiment, UE 100 associates one PTM logical channel with one PTP logical channel based on the association configuration information, but the embodiment is not limited thereto. When receiving MBS services via one or more PTM logical channels, UE 100 may receive association configuration information including information for configuring association between one or more PTP logical channels and one or more PTM logical channels from gNB 200 to configure the association.

[0131] A program that causes a computer to execute each process executed by the UE 100 or the base station 200 (base station 200A, base station 200B) may be provided. The program may be recorded in a computer-readable medium. The use of a computer-readable medium enables the program to be installed on a computer. Here, the computer-readable medium having the program recorded thereon may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM, a DVD-ROM, or the like.

[0132] A circuit for executing a process to be executed by UE 100 or base station 200 (base station 200A, base station 200B) may be integrated, and at least a portion of UE 100 or base station 200 (base station 200A, base station 200B) may be configured as a semiconductor integrated circuit (chip set or SoC).

[0133] The embodiments have been described in detail above with reference to the accompanying drawings, but the specific configurations are not limited to those described above, and various design changes may be made without departing from the gist of the present disclosure.

[0134] This patent application claims the benefit of Japanese Patent Application No. 2020-093497 (filed on May 28, 2020), the entire contents of which are hereby incorporated by reference.

Claims

1. A communication control method, include: The user equipment receives, from the base station, first configuration information for configuring association between a multicast radio bearer configured for MBS transmission and a PTP logical channel; and The user equipment associates the PTP logical channel with the PDCP entity of the multicast radio bearer based on the first setting information.

2. The communication control method according to claim 1, in, The communication control method further includes: The user equipment receives, from the base station, second setting information for setting association between the multicast radio bearer and a PTM logical channel; The user equipment associates the PTM logical channel with the PDCP entity based on the second setting information; and The base station dynamically switches the MBS transmission to the user equipment between the PTM logical channel and the PTP logical channel.

3. A user equipment comprising: a receiving unit receiving, from a base station, first setting information for setting association between a multicast radio bearer configured for MBS transmission and a PTP logical channel; and The control unit associates the PTP logical channel with the PDCP entity of the multicast radio bearer based on the first setting information.

4. A processor controls a user equipment, wherein the processor performs the following processing: receiving, from a base station, first configuration information for configuring association between a multicast radio bearer configured for MBS transmission and a PTP logical channel; and Based on the first setting information, the PTP logical channel is associated with a PDCP entity of the multicast radio bearer.

5. A base station, comprising: The transmitting unit transmits first configuration information for configuring association between a multicast radio bearer configured for MBS transmission and a PTP logical channel to the user equipment.

6. The base station according to claim 5, in, The sending unit sends second setting information for setting association between the multicast radio bearer and the PTM logical channel to the user equipment; The base station further includes a control unit configured to dynamically switch the MBS transmission to the user equipment between the PTM logical channel and the PTP logical channel.

7. A program product, Enable the user equipment to execute the communication control method described in claim 1.

8. A mobile communication system comprising: The user equipment as claimed in claim 3; and a base station.

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