Communication method, user equipment, and base station

Abstract

This communication method, which is used in a mobile communication system, has: a step S1 in which a base station sets a first communication path and a second communication path that is associated with the first communication path to user equipment as communication paths to be established between the base station and the user equipment; a step S2 in which an entity in a prescribed layer of the user equipment maps first data belonging to a data flow to the first communication path; a step S3 in which the entity maps second data to the second communication path, said second data belonging to the data flow and being assigned a higher priority than the first data; and a step S4 in which the user equipment transmits the second data mapped to the second communication path to the base station preferentially before the first data mapped to the first communication path.

Description

[Technical Field]

[0001] The present disclosure relates to a communication method, a user equipment, and a base station for use in a mobile communication system. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project) standard defines the technical specifications for NR (New Radio), a fifth-generation (5G) wireless access technology. NR enables broadband transmission using higher frequency bands than LTE (Long Term Evolution), a fourth-generation (4G) wireless access technology.

[0003] Although NR has the capability to transmit TCP (Transmission Control Protocol) data at high throughput in the downlink, a problem exists in that if the transmission of TCP Ack (Acknowledgement) in the uplink is delayed, the downlink throughput decreases. For this reason, it has been proposed to transmit TCP Ack in the uplink with priority over other data (see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP contribution: RWS-210226, “TCP boosting” Summary of the Invention

[0005] The communication method according to the first aspect is a method used in a mobile communication system. The communication method includes: a base station setting, for a user equipment, a first communication path and a second communication path associated with the first communication path as communication paths established between the base station and the user equipment; an entity of a predetermined layer of the user equipment mapping first data belonging to a data flow to the first communication path; the entity mapping second data belonging to the data flow and having a higher priority than the first data to the second communication path; and the user equipment transmitting the second data mapped to the second communication path to the base station with priority over the first data mapped to the first communication path.

[0006] The user equipment according to the second aspect is a user equipment used in a mobile communication system. The user equipment includes: a receiving unit that receives, from a base station, information for setting a first communication path and a second communication path associated with the first communication path as communication paths established between the base station and the user equipment; a control unit that maps first data belonging to a data flow to the first communication path and maps second data belonging to the data flow and having a higher priority than the first data to the second communication path; and a transmitting unit that transmits the second data mapped to the second communication path to the base station with priority over the first data mapped to the first communication path.

[0007] The base station according to the third aspect is a base station used in a mobile communication system. The base station includes a control unit that sets, for a user equipment, a first communication path and a second communication path associated with the first communication path as communication paths to be established between the base station and the user equipment, and a reception unit that receives, from the user equipment, first data mapped to the first communication path and second data mapped to the second communication path. The first data and the second data belong to the same data flow. The second data mapped to the second communication path is transmitted from the user equipment with higher priority than the first data mapped to the first communication path.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] However, in the current technical specifications of the 3GPP standard, a mechanism for transmitting TCP Ack with higher priority than other data in the uplink has not been introduced. Therefore, there is room for improvement in achieving high throughput in a mobile communication system.

[0010] Therefore, an object of the present disclosure is to enable high throughput to be achieved in a mobile communication system.

[0011] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0012] First, with reference to FIGS. 1 to 7, the configuration of a mobile communication system according to an embodiment will be described. FIG. 1 is a diagram showing the configuration of a mobile communication system according to an embodiment. The mobile communication system 1 complies with the 5th Generation System (5GS) of the 3GPP standard. Hereinafter, the 5GS will be described as an example, but the LTE (Long Term Evolution) system may be at least partially applied to the mobile communication system. Also, the 6th Generation (6G) system may be at least partially applied to the mobile communication system.

[0013] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20.

[0014] UE100 is a movable wireless communication device. UE100 can be any device as long as it is used by a user. For example, UE100 can be a mobile phone terminal (including smartphones), a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided for the sensor, a vehicle or a device provided for the vehicle (Vehicle UE), an aircraft or a device provided for the aircraft (Aerial UE).

[0015] NG-RAN10 includes base stations (referred to as "gNB" in the 5G system) 200. The gNBs 200 are interconnected via the Xn interface which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with the UE100 that has established a connection with its cell. The gNB 200 has functions such as a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), 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 for performing wireless communication with the UE100. One cell belongs to one carrier frequency.

[0016] Note that the gNB can also be connected to the EPC (Evolved Packet Core) which is the core network of LTE. The base station of LTE can also be connected to the 5GC. The base station of LTE and the gNB can also be connected via an interface between base stations.

[0017] 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls and the like for the UE100. The AMF manages the mobility of the UE100 by communicating with the UE100 using NAS (Non-Access Stratum) signaling. The UPF performs data transfer control. The AMF and the UPF are connected to the gNB200 via an NG interface, which is an interface between the base station and the core network.

[0018] Figure 2 is a diagram showing the configuration of a UE100 (user equipment) according to an embodiment. The UE100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130.

[0019] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

[0020] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmitted signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0021] The control unit 130 performs various controls and processes in the UE100. Such processes include the processes of each layer described later. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of the baseband signal. The CPU executes the programs stored in the memory to perform various processes.

[0022] FIG. 3 is a diagram showing the configuration of a gNB 200 (base station) according to an embodiment. The gNB 200 includes a transmission unit 210, a reception unit 220, a control unit 230, and a backhaul communication unit 240.

[0023] The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0024] The reception unit 220 performs various receptions under the control of the control unit 230. The reception unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230.

[0025] The control unit 230 performs various controls and processes in the gNB 200. Such processes include the processes of each layer described later. The control unit 230 includes at least one processor and at least one memory. The memory stores a program executed by the processor and information used for the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals, etc. The CPU executes a program stored in the memory to perform various processes.

[0026] The backhaul communication unit 240 is connected to an adjacent base station via a base station interface, and is connected to the AMF / UPF 300 via a base station-core network interface. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally split), and the two units may be connected by an F1 interface.

[0027] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0028] The wireless interface protocol of the user plane has 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.

[0029] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Between the PHY layer of UE100 and the PHY layer of gNB200, data and control information are transmitted via a physical channel.

[0030] The MAC layer performs data priority control, retransmission processing by Hybrid Automatic Repeat reQuest (HARQ), and random access procedures, etc. Between the MAC layer of UE100 and the MAC layer of gNB200, data and control information are transmitted via a transport channel. The MAC layer of gNB200 includes a scheduler. The scheduler determines the uplink and downlink transport formats (transport block size, modulation and coding scheme (MCS)) and the resource blocks allocated to UE100.

[0031] The RLC layer uses the functions of the MAC layer and the PHY layer to transmit data to the RLC layer on the receiving side. Between the RLC layer of UE100 and the RLC layer of gNB200, data and control information are transmitted via a logical channel.

[0032] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0033] The SDAP layer performs the mapping between the IP flow, which is the unit for the core network to perform QoS (Quality of Service) control, and the radio bearer, which is the unit for the AS (Access Stratum) to perform QoS control. Note that when the RAN is connected to the EPC, the SDAP may not be necessary.

[0034] Figure 5 is a diagram showing the configuration of the protocol stack of the radio interface of the control plane that handles signaling (control signals).

[0035] The protocol stack of the radio interface of the control plane has an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer instead of the SDAP layer shown in Figure 4.

[0036] Between the RRC layer of UE100 and the RRC layer of gNB200, RRC signaling for various settings is transmitted. 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. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in the RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in the RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in the RRC inactive state.

[0037] The NAS layer located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of UE100 and the NAS layer of AMF300a.

[0038] Note that UE100 has an application layer, etc. in addition to the protocol of the radio interface.

[0039] FIG. 6 is a diagram for explaining QoS (Quality of Service) control in the mobile communication system 1 (see 3GPP TS38.300).

[0040] As shown in FIG. 6, in the 5GS mobile communication system 1, in order to enable more flexible and detailed QoS control, QoS control at the QoS flow 32 unit level is possible. A plurality of QoS flows 32 are provided within one PDU session 31 established between the UE 100 and the UPF 300b. At the NAS level, the QoS flow 32 is the finest granularity of QoS control in the PDU session 31. The QoS flow 32 is identified within the PDU session 31 by the QoS flow ID (QFI) transmitted in the encapsulation header in the NG-U tunnel 33 between the gNB (NB) and the UPF 300b.

[0041] At the AS level between the UE 100 and the gNB 200 (NG-RAN 10), QoS control is performed in units of radio bearers (DRBs: Data Radio Bearers) 34. The respective SDAP layers of the UE 100 and the gNB 200 perform mapping between the QoS flow 32 and the radio bearer 34. Specifically, the SDAP layer encapsulates the IP packet and notifies the corresponding QFI in its header (SDAP header).

[0042] In this way, the NG-RAN 10 and the 5GC 20 guarantee the service quality (reliability and / or target delay, etc.) by mapping the packets to the appropriate QoS flows and DRBs. Therefore, there is a two-stage mapping (AS) of mapping from the IP flow to the QoS flow 32 (NAS) and mapping from the QoS flow 32 to the DRB 34.

[0043] At the AS level, data radio bearer (DRB) 34 defines packet processing on the radio interface (Uu). One DRB34 processes packets with the same packet transfer processing. The mapping of QoS flow 32 to DRB34 by NG-RAN10 is based on the QFI and the associated QoS profile (i.e., QoS parameters and QoS characteristics). It is also possible to establish individual DRB34s for QoS flows 32 that require different packet transfer processing, or to multiplex multiple QoS flows 32 belonging to the same PDU session 31 onto the same DRB34.

[0044] Figure 7 is a diagram showing an example of the processing of each layer in the protocol stack of the radio interface of the user plane.

[0045] First, the processing on the transmitting side will be described. The transmitting side SDAP entity, which is an entity of the SDAP layer on the transmitting side, receives the IP packet to be transmitted to the receiving side as an SDAP SDU, performs the transmitting process of the SDAP layer, and generates an SDAP PDU by attaching an SDAP header to the SDAP SDU and outputs it to the lower layer.

[0046] The transmitting side PDCP entity, which is an entity of the PDCP layer on the transmitting side, receives the SDAP PDU as a PDCP SDU, performs the transmitting process of the PDCP layer, and generates a PDCP PDU by attaching a PDCP header to the PDCP SDU and outputs it to the lower layer.

[0047] The transmitting side RLC entity, which is an entity of the RLC layer on the transmitting side, receives the PDCP PDU as an RLC SDU, performs the transmitting process of the RLC layer, and generates an RLC PDU by attaching an RLC header to the RLC SDU and outputs it to the lower layer.

[0048] The transmitting - side MAC entity, which is an entity of the MAC layer on the transmitting side, receives the RLC PDU as a MAC SDU, performs the transmission processing of the MAC layer, and generates a MAC PDU by attaching a MAC header to the MAC SDU, and outputs it to the lower layer.

[0049] Second, the processing on the receiving side will be described. The receiving - side MAC entity, which is an entity of the MAC layer on the receiving side, receives the MAC PDU from the lower layer, performs the receiving processing of the MAC layer based on the MAC header, and removes the MAC header to output the MAC SDU to the upper layer.

[0050] The receiving - side RLC entity, which is an entity of the RLC layer on the receiving side, receives the MAC SDU from the lower layer as an RLC PDU, performs the receiving processing of the RLC layer based on the RLC header, and removes the RLC header to output the RLC SDU to the upper layer.

[0051] The receiving - side PDCP entity, which is an entity of the PDCP layer on the receiving side, receives the RLC SDU from the lower layer as a PDCP PDU, performs the receiving processing of the PDCP layer based on the PDCP header, and removes the PDCP header to output the PDCP SDU to the upper layer.

[0052] The receiving - side SDAP entity, which is an entity of the SDAP layer on the receiving side, receives the PDCP SDU from the lower layer as an SDAP PDU, performs the receiving processing of the SDAP layer based on the SDAP header, and removes the SDAP header to output the SDAP SDU (IP packet) to the upper layer.

[0053] Next, with reference to FIG. 8, the operation of the mobile communication system 1 according to an embodiment will be described. Although the mobile communication system 1 has the ability to transmit TCP data at high throughput in the downlink, due to the TCP mechanism, there is a problem that if the transmission of TCP Ack in the uplink is delayed, the throughput of the downlink decreases. In the following, the operation that enables specific data (for example, TCP Ack) to be transmitted with higher priority than other data in the uplink will be described.

[0054] As shown in FIG. 8, in step S1, the gNB 200 sets, for the UE 100, a first communication path and a second communication path associated with the first communication path as communication paths to be established between the gNB 200 and the UE 100. Here, the gNB 200 may transmit an RRC message including information for associating the first communication path and the second communication path to the UE 100.

[0055] In step S2, an entity of a predetermined layer of the UE 100 (hereinafter referred to as "predetermined entity") maps first data belonging to a data flow to the first communication path.

[0056] In step S3, the predetermined entity of the UE 100 maps second data belonging to the data flow and having a higher priority than the first data to the second communication path. The second data may be TCP Ack.

[0057] The predetermined layer may be the SDAP layer. That is, the predetermined entity may be the SDAP entity (transmission-side SDAP entity) of the UE 100. The first communication path may be a general DRB, and the second communication path may be a priority DRB associated with the general DRB.

[0058] Alternatively, the predetermined layer may be a PDCP layer. That is, the predetermined entity may be the PDCP entity (transmission-side PDCP entity) of the UE 100. The first communication path may be the general leg of the split bearer. The second communication path may be the priority leg of the split bearer.

[0059] In step S4, the UE 100 transmits the second data mapped to the second communication path to the gNB 200 with higher priority than the first data mapped to the first communication path. For example, the MAC entity (transmission-side MAC entity) of the UE 100 performs a process (LCP: Logical Channel Prioritization) that prioritizes the second logical channel associated with the second communication path over the first logical channel associated with the first communication path. Generally, the parameters for the LCP process are set for the UE 100 by the gNB 200.

[0060] This enables specific data (e.g., TCP Ack) to be transmitted with higher priority than other data in the uplink. Therefore, high throughput can be achieved in the mobile communication system 1.

[0061] In the UE 100 according to an embodiment, the receiving unit 110 receives from the gNB 200 information for setting a first communication path and a second communication path associated with the first communication path as communication paths to be established between the gNB 200 and the UE 100. The control unit 130 maps the first data belonging to the data flow to the first communication path, and maps the second data belonging to the data flow and having a higher priority than the first data to the second communication path. The transmitting unit 120 transmits the second data mapped to the second communication path to the gNB 200 with higher priority than the first data mapped to the first communication path.

[0062] In the gNB200 according to one embodiment, the control unit 230 sets, for the UE100, a first communication path and a second communication path associated with the first communication path as communication paths to be established between the gNB200 and the UE100. The transmission unit 210 may transmit an RRC message including information associating the first communication path and the second communication path to the UE100. The reception unit 220 receives first data mapped to the first communication path and second data mapped to the second communication path from the UE100. Here, the first data and the second data are data belonging to the same data flow. The second data mapped to the second communication path is transmitted from the UE100 with higher priority than the first data mapped to the first communication path.

[0063] The second data transmitted with higher priority than the first data in the uplink is not limited to TCP Ack, and data of a type specified by the gNB200 may be used as the second data. For example, the gNB200 sets the type of data to be mapped to the second communication path for the UE100. A predetermined entity of the UE100 maps the data of the set type to the second communication path as the second data. This enables more flexible control.

[0064] As described above, according to one embodiment, it is possible to transmit specific data (e.g., TCP Ack) with higher priority than other data in the uplink. Therefore, it is possible to achieve high throughput in the mobile communication system 1.

[0065] (Example) Next, based on the above-described embodiment, a first example and a second example will be described. These examples are not limited to the case where they are implemented separately and independently, and two or more examples may be combined and implemented. Also, in the operation flows of the following examples, it is not always necessary to execute all steps, and only some steps may be executed. Also, in the operation flows of the following examples, the order of the steps may be changed.

[0066] (1) First Example FIG. 9 is a diagram showing the SDAP entity 101 in the first embodiment. In the first embodiment, a predetermined entity of the UE 100 is the SDAP entity 101 of the UE 100, the first communication path is the Normal DRB 51A, and the second communication path is the Priority DRB 52A associated with the Normal DRB 51A.

[0067] Five QoS flows are input to the SDAP entity 101 of the UE 100. An individual QFI is assigned to each QoS flow, and five QFIs (QFI#1 to #5) are assigned to the five QoS flows.

[0068] The SDAP entity 101 of the UE 100 maps three QoS flows of QFI#1 to #3 to the Normal DRB 51A according to the setting from the gNB 200. The Normal DRB 51A is assigned "#1" as the DRB ID. Also, the SDAP entity 101 maps two QoS flows of QFI#4 and # 5 to the Normal DRB 53 according to the setting from the gNB 200. The Normal DRB 53 is assigned "#3" as the DRB ID.

[0069] The Priority DRB 52A is associated with the Normal DRB 51A according to the setting from the gNB 200. The Priority DRB 52A is assigned "#2" as the DRB ID.

[0070] The SDAP entity 101 of UE100 maps and outputs the first data (e.g., TCP data other than TCP Ack) belonging to three QoS flows of QFI#1 to #3 to the general DRB51A. Also, the SDAP entity 101 of UE100 maps and outputs the second data (e.g., TCP Ack) belonging to the three QoS flows to the priority DRB52A. Here, the mapping to the priority DRB52A means reassigning the data of the QoS flow assigned to the general DRB51A according to the setting from gNB200 to the priority DRB52A. Therefore, such mapping may be called Remapping. As a result, the second data (e.g., TCP Ack) can be preferentially transmitted.

[0071] Here, among the three QoS flows of QFI#1 to #3, the QoS flow that enables mapping to the priority DRB52A may be set by gNB200. For example, among the three QoS flows of QFI#1 to #3, the two QoS flows of QFI#1 and #2 may be enabled for mapping to the priority DRB52A, and the QoS flow of QFI#3 may be prohibited from mapping to the priority DRB52A. As a result, the applicability of the priority DRB52A can be flexibly set for each QoS flow.

[0072] The SDAP entity 101 of UE100 may generate one SDAP PDU including two or more TCP Acks belonging to two or more QoS flows, and map and output the SDAP PDU to the priority DRB52A. Specifically, the Remapping function of the SDAP entity 101 may concatenate a plurality of TCP Ack packets of a plurality of QoS flows, generate an SDAP header including the QFI of each of the plurality of QoS flows, and generate one SDAP PDU having the concatenated plurality of TCP Ack packets and the SDAP header. As a result, TCP Ack can be efficiently transmitted.

[0073] Note that the priority DRB52A may be associated with only one general DRB51A. For example, the two QoS flows of QFI#4 and #5 assigned to the general DRB53 are prohibited from being mapped to the priority DRB52A.

[0074] FIG. 10 is a diagram showing the operations of the gNB200 and the UE100 in the first embodiment.

[0075] In step S101, the gNB200 sets a mapping rule for the UE100. Specifically, the gNB200 sets a special DRB (priority DRB52A) for the UE100. Also, the gNB200 sets a general DRB51A that can map data to the priority DRB52A for the UE100. That is, the gNB200 permits the UE100 to remap the data mapped to the general DRB51A to the priority DRB52A. The gNB200 may set for the UE100 the association information between the DRB ID "#1" of the priority DRB52A and the DRB ID "2" of the general DRB51A. The setting in step S101 may be performed by a UE-dedicated RRC message transmitted from the gNB200 to the UE100, for example, an RRC Reconfiguration message. The UE100 receives an RRC message including the setting information from the gNB200.

[0076] In step S101, the gNB200 may set for the UE100 the data type of the IP packet that can be remapped to the priority DRB52A (or permit remapping to the priority DRB52A) (priority transmission data setting). For example, the gNB200 may set TCP Ack as the data type. Also, for example, the gNB200 may set UDP (User Datagram Protocol) data.

[0077] In step S101, gNB200 may set for UE100 a QFI (QoS flow) that can be mapped to the priority DRB52A (priority transmission target QFI setting). For example, when there are QFIs #1 to #3 mapped to the general DRB51A, gNB200 may perform a setting for UE100 indicating that the QFIs that can be mapped to the priority DRB52A are #1 and #2.

[0078] In step S102, the SDAP entity 101 of UE100 receives an SDAP SDU (i.e., an IP packet) from the upper layer. Note that the SDAP SDU is not limited to an IP packet and may be an industrial Ethernet packet or the like. In the following, an example where the SDAP SDU is an IP packet will be described. The QFI of the QoS flow to which the SDAP SDU (IP packet) belongs is associated with the DRB ID of the general DRB according to the mapping rule.

[0079] In step S103, the SDAP entity 101 of UE100 may determine whether the QFI of the QoS flow to which the SDAP SDU received in step S102 belongs is set as a QFI (QoS flow) that can be mapped to the priority DRB52A. In the case of a QFI that can be mapped to the priority DRB52A (step S103: YES), the process proceeds to step S104. On the other hand, in the case of a QFI that cannot be mapped to the priority DRB52A (step S103: NO), the process proceeds to step S105. Step S103 is not essential in the operation of UE100 in FIG. 10.

[0080] In step S104, the SDAP entity 101 of UE100 determines whether the SDAP SDU received in step S102 is priority transmission data to be preferentially transmitted. The priority transmission data may be data of a predefined type (e.g., TCP Ack). Also, the priority transmission data may be data of the type set by gNB200 in step S101.

[0081] The SDAP entity 101 of the UE 100 may perform deep packet inspection (DPI) or the like to determine whether the data to be preferentially transmitted. The SDAP entity 101 of the UE 100 can discriminate TCP Ack by header analysis of the SDAP SDU (IP packet). For example, if the "Protocol" field of the IP header is "6", the SDAP entity 101 of the UE 100 may determine that it is a TCP packet. Alternatively, if the "ACK" bit in the "control flag" of the TCP header is "1", the SDAP entity 101 of the UE 100 may determine that it is a TCP Ack packet.

[0082] If it is determined that the SDAP SDU received in step S102 is not preferentially transmitted data (step S104: NO), in step S105, the SDAP entity 101 of the UE 100 maps the SDAP SDU to the general DRB51A and outputs the SDAP PDU configured to include the SDAP SDU to the general DRB51A.

[0083] On the other hand, if it is determined that the SDAP SDU received in step S102 is preferentially transmitted data (step S104: YES), in step S106, the SDAP entity 101 of the UE 100 maps the SDAP SDU to the priority DRB52A and outputs the SDAP PDU configured to include the SDAP SDU to the priority DRB52A. Here, the remapping function of the SDAP entity 101 may concatenate a plurality of TCP Ack packets (a plurality of SDAP SDUs) of a plurality of QoS flows to generate one SDAP PDU. At that time, by including the QFI of the plurality of SDAP SDUs in the SDAP header, a plurality of QFIs may be notified by the SDAP header.

[0084] Note that the SDAP entity 101 of the UE 100 may add an SDAP header according to the settings from the gNB 200 in both steps S105 and S106. Even if there is no setting for adding an SDAP header, when multiple QoS flows are remapped to the priority DRB 52A, the SDAP entity 101 of the UE 100 may always add an SDAP header so that the receiving side can know the QFI of each packet.

[0085] In steps S107 and S108, the lower layer (especially the MAC entity) of the UE 100 transmits the data mapped to the priority DRB 52A with higher priority than other DRBs. For example, the MAC entity may handle the data mapped to the priority DRB 52A as the highest priority in the LCP. Note that the gNB 200 may set the priority. The gNB 200 receives the data mapped to the priority DRB 52A.

[0086] (2) Second Embodiment FIG. 11 is a diagram showing the PDCP entity 102 in the second embodiment. In the second embodiment, the predetermined entity of the UE 100 is the PDCP entity 102 of the UE 100. The first communication path is the normal leg 51B of the split bearer, and the second communication path is the prioritized-leg 52B of the split bearer. Note that the leg may be an RLC channel or a logical channel.

[0087] One DRB (DRB#1) corresponding to one data flow is input to the PDCP entity 102 of the UE 100. The PDCP entity 102 of the UE 100 forms a split bearer by splitting (splitting) DRB#1 into a general leg 51B and a priority leg 52B according to the settings from the gNB 200. The logical channel (LCH) ID "#1" is assigned to the general leg 51B. The LCH ID "#2" is assigned to the priority leg 52B. Note that there may be three or more legs.

[0088] The PDCP entity 102 of the UE 100 maps (routes) and outputs the first data (for example, TCP data other than TCP Ack) belonging to DRB#1 to the general leg 51B. Also, the PDCP entity 102 of the UE 100 maps (routes) and outputs the second data (for example, TCP Ack) belonging to DRB#1 to the priority leg 52B.

[0089] FIG. 12 is a diagram showing the operations of the gNB 200 and the UE 100 in the second embodiment.

[0090] In step S201, the gNB 200 performs split bearer settings for the UE 100. The settings may include identification information of the general leg 51B and / or the priority leg 52B. The settings may include the data types that can be mapped (routed) to the priority leg 52B. The settings in step S201 may be performed by a UE-dedicated RRC message transmitted from the gNB 200 to the UE 100, for example, an RRC Reconfiguration message. The UE 100 receives an RRC message including the setting information from the gNB 200.

[0091] Here, regarding the identification information of the general leg 51B and / or the priority leg 52B, the information may be associated with the entire split bearer (for example, "TCP Ack prioritization=true"). The identification information may be associated with each leg. The identification information may be associated with each RLC channel (RLC bearer / RLC entity). The identification information may be associated with each LCH.

[0092] In step S202, the PDCP entity 102 of the UE 100 receives a PDCP SDU (for example, a PDCP SDU belonging to DRB#1) from the SDAP entity.

[0093] In step S203, the PDCP entity 102 of the UE 100 determines whether the PDCP SDU received in step S202 is priority transmission data to be preferentially transmitted. The priority transmission data may be data of a predefined type (for example, TCP Ack). Also, the priority transmission data may be data of the type set by the gNB 200 in step S101. Note that the determination of whether it is priority transmission data or the determination of the data type may be performed by the SDAP entity, and the determination result may be notified from the SDAP entity to the PDCP entity 102. The method for determining the priority transmission data is the same as that of the first embodiment described above. Alternatively, the determination of whether it is priority transmission data or the determination of the data type may be performed by the PDCP entity. The method for determining the priority transmission data is the same as the method applicable to the first embodiment described above.

[0094] If it is determined that the PDCP SDU received in step S202 is not priority transmission data (step S203: NO), in step S204, the PDCP entity 102 of the UE 100 maps (routes) the PDCP SDU to the general leg 51B and outputs a PDCP PDU configured to include the PDCP SDU to the general leg 51B.

[0095] On the one hand, when it is determined that the PDCP SDU received in step S202 is priority transmission data (step S203: YES), in step S205, the PDCP entity 102 of UE100 maps (routes) the PDCP SDU to the priority leg 52B and outputs a PDCP PDU configured to include the PDCP SDU to the priority leg 52B.

[0096] In steps S206 and S207, the lower layer of UE100 (specifically, the MAC entity) transmits the data mapped to the priority leg 52B with higher priority than other legs. For example, the MAC entity may treat the data mapped to the priority leg 52B as the highest priority in LCP. Note that gNB200 may set the priority. gNB200 receives the data mapped to the priority leg 52B.

[0097] (Other embodiments) Each of the above operation flows is not limited to being implemented separately and independently, but two or more operation flows can be combined and implemented. For example, some steps of one operation flow may be added to another operation flow. Also, some steps of one operation flow may be replaced with some steps of another operation flow.

[0098] In the above embodiments and examples, an example where the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB) or a 6G base station. Also, the base station may be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may be the DU (Distributed Unit) of the IAB node. Also, the user equipment may be the MT (Mobile Termination) of the IAB node. In the above embodiments and examples, the Uu link (communication between the base station and the UE) has been described as an example, but it may be applied to the sidelink (direct communication between UEs). Also, the above embodiments and examples may be applied to a sidelink relay UE using the sidelink.

[0099] A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded on a computer-readable medium. By using the computer-readable medium, it is possible to install the program in the computer. Here, the computer-readable medium on which the program is recorded 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 or a DVD-ROM. Further, a circuit that executes each process performed by the UE 100 or the gNB 200 may be integrated, and at least a part of the UE 100 or the gNB 200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0100] As used in this disclosure, the terms "based on" and "depending on" do not mean "only based on" or "only depending on" unless otherwise specified. The term "based on" means both "only based on" and "at least partially based on". Similarly, the term "depending on" means both "only depending on" and "at least partially depending on". Also, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from other nodes, or obtaining the information by generating the information. The terms "include", "comprise", and their variants do not mean including only the listed items, but may include only the listed items or may further include additional items in addition to the listed items. Also, the term "or" used in this disclosure is not intended to be an exclusive disjunction. Further, any reference to an element using designations such as "first", "second", etc. used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this specification as a convenient way to distinguish between two or more elements. Thus, a reference to a first and a second element does not mean that only two elements may be employed there or that the first element must precede the second element in some form. In this disclosure, for example, when articles are added by translation, such as a, an, and the in English, these articles shall be construed to include plural ones unless the context clearly indicates otherwise.

[0101] As described above in detail with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist.

[0102] This application claims the priority of Japanese Patent Application No. 2021-116738 (filed on July 14, 2021), and all of its content is incorporated into the specification of this application.

Explanation of Reference Numerals

[0103] 1: Mobile communication system 31: PDU session 32: QoS flow 33: NG-U tunnel 34: Radio bearer 51A: General DRB 52A: Priority DRB 51B: General leg 52B: Priority leg 53: General DRB 101: SDAP entity 102: PDCP entity 100: UE 110: Receiver 120: Transmitter 130: Control unit 200: gNB 210: Transmitter 220: Receiver 230: Control unit 240: Backhaul communication unit

Claims

1. A communication method used in a mobile communication system, wherein a network node sets, for a user equipment, a first communication path and a second communication path associated with the first communication path as communication paths to be established between the network node and the user equipment; an entity of a predetermined layer of the user equipment maps first data belonging to a data flow to the first communication path; the entity maps second data, which is data belonging to the data flow and is given a higher priority than the first data, to the second communication path; the user equipment transmits the second data mapped to the second communication path to the network node with priority over the first data mapped to the first communication path; and the setting includes transmitting, from the network node to the user equipment, an RRC Reconfiguration message including information associating the first communication path with the second communication path Communication method.

2. The second data is TCP Ack (Transmission Control Protocol Acknowledgment). The communication method according to claim 1.

3. The network node further has a step of setting, for the user equipment, a type of data to be mapped to the second communication path, wherein mapping to the second communication path includes mapping data of the set type to the second communication path as the second data. The communication method according to claim 1 or 2.

4. The predetermined layer is an SDAP (Service Data Adaptation Protocol) layer, the data flow is a QoS flow, the first communication path is a general DRB (Data Radio Bearer), and the second communication path is a priority DRB associated with the general DRB. The communication method according to claim 1.

5. Mapping to the first communication path includes mapping the first data belonging to a plurality of QoS flows to the general DRB, and mapping to the second communication path includes mapping the second data belonging to at least one QoS flow among the plurality of QoS flows to the priority DRB. The communication method according to claim 4.

6. The method according to claim 5, further comprising: the network node sets, for the user equipment, at least one QoS flow that enables mapping to the priority DRB. The communication method according to claim 5.

7. The second data is a TCP Ack, and mapping to the second communication path includes: mapping one SDAP PDU (Protocol Data Unit) including two or more TCP Acks belonging to two or more QoS flows among the plurality of QoS flows to the second communication path. The communication method according to claim 5 or 6.

8. The predetermined layer is a PDCP (Packet Data Convergence Protocol) layer, the first communication path is a general leg of a split bearer, and the second communication path is a priority leg of the split bearer. The communication method according to claim 1 or 2.

9. The setting includes: setting the split bearer for the user equipment. The communication method according to claim 8.

10. The predetermined layer is an SDAP (Service Data Adaptation Protocol) layer, The communication method according to claim 1, wherein the entity adds an SDAP header to an SDAP SDU (Service Data Unit) even when there is no setting for adding an SDAP header.

11. A user equipment used in a mobile communication system, comprising: a receiving unit that receives, from a network node, information for setting a first communication path and a second communication path associated with the first communication path as communication paths established between the network node and the user equipment; a control unit that maps first data belonging to a data flow to the first communication path and maps second data belonging to the data flow and having a higher priority than the first data to the second communication path; a transmitting unit that transmits the second data mapped to the second communication path to the network node with priority over the first data mapped to the first communication path; wherein the receiving unit receives, from the network node, an RRC Reconfiguration message including information for associating the first communication path with the second communication path as the information. User equipment.

12. A network node used in a mobile communication system, a control unit that sets, for a user equipment, a first communication path and a second communication path associated with the first communication path as communication paths to be established between the network node and the user equipment; a receiving unit that receives first data mapped to the first communication path and second data mapped to the second communication path from the user equipment; a transmitting unit that transmits an RRC Reconfiguration message including information associating the first communication path and the second communication path to the user equipment, and has: the first data and the second data are data belonging to the same data flow; the second data mapped to the second communication path is transmitted from the user equipment with higher priority than the first data mapped to the first communication path network node.

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