COMMUNICATION CONTROL METHOD, BASE STATION, AND PROCESSOR

Abstract

This communication control method comprises: a first user device being in a mutual discovery state with a second user device, and acquiring second identification information for identifying the second user device; and the second user device acquiring first identification information for identifying the first user device. The communication control method further comprises the first user device transmitting the second identification information to the communication device, and the second user device transmitting the first identification information to a communication device. The communication control method further comprises the communication device setting up a first data radio bearer for the first user device in response to receiving the second identification information, and setting up a second data radio bearer for the second user device in response to receiving the first identification information. The communication control method further comprises the communication device transferring the data, received from the first user device over the first data radio bearer, to the second user device over the second data radio bearer, without transfer to a core network.

Description

Communication Control Method

[0001] The present disclosure relates to a communication control method for use in a cellular communication system.

[0002] In the Third Generation Partnership Project (3GPP), a standardization project for cellular communication systems, various routing techniques for user data are being considered. For example, in a fifth-generation (5G) cellular communication system, a functional block called a User Plane Function (UPF) routes user data.

[0003] 3GPP TS 38.300 V16.6.0 (2021-06)

[0004] A communication control method according to a first aspect includes a first user device and a second user device being in a mutual discovery state, acquiring second identification information identifying the second user device, and the second user device acquiring first identification information identifying the first user device. The communication control method also includes the first user device transmitting the second identification information to a communication device, and the second user device transmitting the first identification information to the communication device. The communication control method further includes the communication device establishing a first data radio bearer for the first user device in response to receiving the second identification information, and establishing a second data radio bearer for the second user device in response to receiving the first identification information. The communication control method also includes the communication device forwarding first data received from the first user device using the first data radio bearer to the second user device using the second data radio bearer without forwarding the data to a core network.

[0005] A communication control method according to a second aspect includes a step of transmitting, to a base station, a discovery identifier of a second user equipment acquired by a first user equipment when the first user equipment discovers the second user equipment. The communication control method also includes the base station, in response to receiving the discovery identifier, inquiring of a user equipment subordinate to the base station as to whether the user equipment has a discovery identifier. The communication control method also includes the second user equipment responding to the inquiry. The communication control method also includes the base station, in response to the response, establishing a first data radio bearer for the first user equipment and establishing a second data radio bearer for the second user equipment. The communication control method also includes the base station forwarding, to the second user equipment, first data received from the first user equipment via the first data radio bearer, without forwarding the data to a core network, via the second data radio bearer.

[0006] A communication control method according to a third aspect includes a base station forwarding data received from the first user equipment to a second user equipment using a data radio bearer without forwarding the data to a core network, and the base station transmitting a data amount of the data to the core network.

[0007] FIG. 1 is a diagram illustrating an example of the configuration of a cellular communication system according to one embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a UE (user equipment) according to one embodiment. FIG. 3 is a diagram illustrating an example of the configuration of a gNB (base station) according to one embodiment. FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack related to a user plane according to one embodiment. FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack related to a control plane according to one embodiment. FIGS. 6(A) and 6(B) are diagrams illustrating an example of routing according to the first embodiment. FIG. 7 is a diagram illustrating an example of local routing according to the first embodiment. FIG. 8 is a diagram illustrating an example of a protocol stack according to the first embodiment. FIG. 9 is a diagram illustrating an example of operation according to the first embodiment. FIG. 10 is a diagram illustrating an example of operation according to the second embodiment. FIG. 11 is a diagram illustrating an example of operation according to the third embodiment. FIG. 12 is a diagram illustrating an example of operation according to the fourth embodiment.

[0008] An object of the present disclosure is to provide a communication control method that allows routing to be performed appropriately.

[0009] A cellular 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.

[0010] (Cellular communication system) First, a configuration of a cellular communication system according to an embodiment will be described. The cellular communication system according to an embodiment is a 3GPP 5G system, but LTE may be applied at least in part to the cellular communication system. Furthermore, future cellular communication systems such as 6G may also be applied to the cellular communication system.

[0011] FIG. 1 is a diagram illustrating an example of the configuration of a cellular communication system according to an embodiment.

[0012] As shown in FIG. 1, the cellular communication system 1 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: 5G Core Network) 20.

[0013] The UE 100 is a mobile device. The UE 100 may be any device that is used by a user, and may be, for example, a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0014] The NG-RAN 10 includes a base station (called a "gNB" in a 5G system) 200. The gNB 200 is sometimes called an NG-RAN node. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has 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, and the like. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with a UE 100. One cell belongs to one carrier frequency.

[0015] The gNB may be connected to the Evolved Packet Core (EPC), which is an LTE core network, or the LTE base station may be connected to the 5GC 20. The LTE base station and the gNB may be connected via an inter-base station interface.

[0016] The 5GC20 includes an AMF (Access and Mobility Management Function) 301 (301-1, 301-2) and a UPF (User Plane Function) 302 (302-1, 302-2). The AMF 301 performs various mobility controls for the UE 100. The AMF 301 manages information about the area in which the UE 100 is located by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF 302 controls data forwarding. The AMF 301 and the UPF 302 are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network. AMF301 and UPF302 are examples of core network devices connected to 5GC (core network) 20.

[0017] FIG. 2 is a diagram illustrating an example of the configuration of a UE 100 (user equipment) according to an embodiment.

[0018] As shown in FIG. 2 , the UE 100 includes a receiving unit 110 , a transmitting unit 120 , and a control unit 130 .

[0019] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal 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 (up-converts) a baseband signal (transmission 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 in the UE 100. The control unit 130 includes at least one processor and at least one memory electrically connected to the processor. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. The control unit 130 may perform various processes executed by the UE 100 in each of the embodiments described below.

[0022] Figure 3 is a diagram showing an example configuration of a gNB200 (base station) according to one embodiment.

[0023] As shown in FIG. 3, gNB200 has a transmitter 210, a receiver 220, a control unit 230, and a backhaul communication unit 240.

[0024] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts (up-converts) a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0025] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0026] The control unit 230 performs various controls in the gNB 200. The control unit 230 includes at least one processor and at least one memory electrically connected to the processor. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. The control unit 230 may perform various processes executed by the gNB 200 in each of the embodiments described below.

[0027] The backhaul communication unit 240 is connected to adjacent base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF 301 and / or the UPF 302 via a base station-core network interface. The gNB is composed of a CU (Central Unit) and a DU (Distributed Unit), and the two units may be connected via an F1 interface.

[0028] FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack of a radio interface of a user plane according to an embodiment.

[0029] As shown in FIG. 4, the radio interface protocol of the user plane that handles data 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.

[0030] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the gNB 200 via a physical channel.

[0031] The MAC layer performs data priority control, retransmission processing using hybrid ARQ (HARQ), random access procedures, 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 uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[0032] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0033] The PDCP layer performs header compression / decompression, and encryption / decryption. Data and control information are transmitted between the PDCP layer of the UE 100 and the PDCP layer of the gNB 200 via a radio bearer.

[0034] The SDAP layer maps QoS flows, which are units for QoS control by the core network, to radio bearers, which are units for QoS control by an AS (Access Stratum). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0035] FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack of a radio interface of a control plane according to an embodiment.

[0036] As shown in FIG. 5, the protocol stack of the radio interface of the control plane that handles signaling (control signals) has an RRC (Radio Resource Control) layer and a NAS layer instead of the SDAP layer shown in FIG.

[0037] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. Also, when the RRC connection is suspended, UE100 is in an RRC inactive state.

[0038] The NAS layer, which is located above 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 301.

[0039] In addition, the UE 100 has an application layer and the like in addition to the radio interface protocol.

[0040] First Embodiment Next, a first embodiment will be described.

[0041] The first embodiment is an embodiment related to routing. Here, an example of routing according to the first embodiment will be described.

[0042] (Example of Routing) Fig. 6A is a diagram showing an example of routing according to the first embodiment. Routing is, for example, selecting a path so that data (packets) transmitted from a source can be transmitted correctly to a destination (or transmission destination). Generally, routing is performed at the IP (Internet Protocol) layer.

[0043] In a 5G system, the UPF 302 can perform processing on the IP layer. Therefore, as shown in FIG. 6A, the UPF 302 performs routing. Since the UPF 302 performs routing, the example of FIG. 6A shows an example in which a MEC (Mobile Edge Computing) server 400 is connected to the UPF 302.

[0044] FIG. 6(B) is a diagram showing an example of routing according to the first embodiment. As shown in FIG. 6(B), in the cellular communication system 1, a technology for connecting to the Internet without going through a core network has also been proposed. Such a technology may be referred to as local breakout. Local breakout is also an example of routing. Note that the example of FIG. 6(B) shows an example in which routing is performed by a GW connected to the gNB 200.

[0045] Furthermore, there is a locally routed mode in D2D (Device to Device) communication in which a plurality of nearby UEs 100 perform data communication directly without going through a core network. The locally routed mode is a mode in which a data path goes through an eNB (evolved Node B), unlike a direct communication mode in which a data path does not go through an eNB.

[0046] The examples shown in FIGS. 6A and 6B mainly show an example in which routing is performed in layer 3 (IP layer).

[0047] However, in 5G system communications, as shown in Figure 6 (A), even when UE100-1 and UE100-2 are within the coverage of the same gNB200, data transmitted from UE100-1 reaches the core network (UPF302) and is returned via the same route.

[0048] In such cases, if data could be routed without going through the core network, it would be possible to reduce the amount of traffic in the core network and reduce delays that occur in communications within the core network. Routing that does not go through the core network is sometimes called local routing.

[0049] 7 is a diagram showing an example of local routing according to the first embodiment. As shown in FIG. 7, it is also possible for the gNB 200 to perform local routing. However, although the gNB 200 can perform processing for Layer 2 (SDAP layer (or PDCP layer)), it cannot perform processing for Layer 3 (IP layer).

[0050] Therefore, there is a challenge in how to perform local routing using Layer 2 in gNB200.

[0051] Therefore, in the first embodiment, when the UE 100-1 and the UE 100-2 are in a discovery state, the UE 100-1 transmits RAN (Radio Access Network) identification information to the gNB 200. Then, in response to receiving the RAN identification information, the gNB 200 sets a data radio bearer (DRB) for local routing for the UE 100-1. The gNB 200 transfers the data transmitted from the UE 100-1 using the DRB to the UE 100-2 without transferring it to the core network.

[0052] Specifically, first, a first user apparatus (e.g., UE 100-1) and a second user apparatus (e.g., UE 100-2) are in a mutual discovery state, and acquire second identification information identifying the second user apparatus, while the second user apparatus acquires first identification information identifying the first user apparatus. Second, the first user apparatus transmits the second identification information to a communication apparatus (e.g., gNB 200), and the second user apparatus transmits the first identification information to the communication apparatus. Third, in response to receiving the second identification information, the communication apparatus sets a first data radio bearer for the first user apparatus, and in response to receiving the first identification information, sets a second data radio bearer for the second user apparatus. Fourth, the communication apparatus forwards the first data received from the first user apparatus using the first data radio bearer to the second user apparatus using the second data radio bearer without forwarding the data to the core network.

[0053] FIG. 8 is a diagram showing an example of a protocol stack according to the first embodiment. The SDAP layer or PDCP layer (Layer 2) is a layer capable of performing processing related to a data radio bearer (DRB). As shown in FIG. 8, the gNB 200 can handle the SDAP layer (or PDCP layer). By configuring a DRB for local routing for the UE 100-1 (and the UE 100-2), the gNB 200 can forward data transmitted from the UE 100-1 using the DRB to the UE 100-2 without forwarding it to the core network. Therefore, the gNB 200 is capable of routing using Layer 2. Note that the SDAP sublayer may not be required in this protocol stack. In this case, the local routing layer is located above the PDCP sublayer.

[0054] (Operation Example of First Embodiment) FIG. 9 is a diagram showing an operation example according to the first embodiment.

[0055] The operation example shown in Figure 9 represents an example of local routing in which gNB200 forwards data transmitted from UE100-1 to UE100-2 without forwarding it to UPF302, similar to the configuration example of cellular communication system 1 shown in Figure 7.

[0056] It should be noted that the UE 100-1 is connected to the gNB 200, but the UE 100-2 may not be connected to the gNB 200. When the UE 100-2 is not connected to the gNB 200, the UE 100-2 is assumed to be connected to another gNB.

[0057] In addition, hereinafter, UE #1 may be referred to as UE 100-1, and UE #2 may be referred to as UE 100-2.

[0058] As shown in FIG. 9, in step S10, the UE 100-1 and the UE 100-2 are in a discovery state with each other. The UE 100-1 may discover the UE 100-2 using a discovery function, and the UE 100-2 may also discover the UE 100-1 using a discovery function, thereby entering a discovery state with each other. The discovery function may be a function that uses direct discovery of proximity service (Prose (Proximity-based services)) communication. Furthermore, the discovery function may be a function that uses the Open Connectivity Foundation.

[0059] In step S11, the UE 100-1 may request the UE 100-2 to share the RAN identification information. For example, the UE 100-1 may transmit the request to the UE 100-2 by using direct communication of the proximity service.

[0060] Here, the RAN identification information is identification information of the UE 100 on the RAN.

[0061] First, the RAN identification information includes a PLMN ID (Public Land Mobile Network ID), a gNB ID, a cell ID, and a C-RNTI (Cell radio-Radio Network Temporary Identifier). By including these four pieces of identification information in the RAN identification information, it is possible to identify the UE 100 within a specific cell in a specific base station of a specific operator.

[0062] Second, the RAN identity may be an International Mobile Subscriber Identity (IMSI) or a 5g-S Temporary Mobile Subscriber Identity (TMSI).

[0063] Third, the RAN identification information may be a Proximity-based services ID (Prose ID) for sidelink communication. Examples of the Prose ID include a Destination Layer-2 ID and / or a Source Layer-2 ID.

[0064] Fourth, the RAN identification information may include an IP address or an ID of the application layer (including the platform layer).

[0065] In step S12, the UE 100-1 shares RAN identification information with the UE 100-2. For example, the UE 100-1 may acquire the RAN identification information of the UE 100-2 from the UE 100-2 by using direct communication of the proximity service. Furthermore, the UE 100-2 may also acquire the RAN identification information of the UE 100-1 from the UE 100-1 by using direct communication of the proximity service. The UE 100-1 and the UE 100-2 share the RAN identification information by acquiring each other's RAN identification information.

[0066] In step S13, the UE 100-1 transmits the RAN identification information of the UE 100-2 to the gNB 200. The transmission of the RAN identification information may function as a request for local routing.

[0067] In step S14, the gNB 200 configures a DRB for local routing for the UE 100-1 in response to receiving the RAN identification information. The gNB 200 may configure a DRB for local routing by transmitting an RRC message including radio bearer configuration information (radioBearerConfig) to the UE 100-1.

[0068] The DRB is a DRB used by the UE 100-1 when transmitting data addressed to the UE 100-2. The DRB may be a DRB used by the UE 100-1 when receiving data transmitted from the UE 100-2. The UE 100-1 can transmit data addressed to the UE 100-2 by mapping the data addressed to the UE 100-2 to the DRB. Therefore, the DRB may be linked to the RAN identification information of the UE 100-2 as restriction information.

[0069] In addition, if UE100-2 is under the control of another gNB, gNB200 may establish a tunnel session for data forwarding to the other gNB.

[0070] In step S15, UE100-2 transmits the RAN identification information of UE100-1 to gNB200, similar to step S13.

[0071] In step S16, similar to step S14, the gNB200 configures a DRB for local routing for the UE100-2 in response to receiving the RAN identification information. In this case, the gNB200 links the DRB configured for the UE100-1 with the DRB configured for the UE100-2. This enables the gNB200 to route the communication path between the UE100-1 and the gNB200 and the communication path between the UE100-2 and the gNB200.

[0072] In step S17, the UE 100-1 transmits data addressed to the UE 100-2. The UE 100-1 can transmit the data on the DRB for local routing by mapping the data to the DRB for local routing set in step S14.

[0073] In step S18, the gNB 200 performs local routing on the data received from the UE 100-1. The gNB 200 forwards the data to the UE 100-2 without forwarding it to the core network. For example, local routing may be performed as follows.

[0074] The gNB 200 associates the DRB for local routing (step S16) for the UE 100-2 with the DRB for local routing (step S14) set for the UE 100-1. Therefore, the gNB 200 can transfer data transmitted using the DRB for local routing set for the UE 100-1 to the DRB for local routing set for the UE 100-2 by mapping it to the DRB for local routing set for the UE 100-2.

[0075] In the example of Figure 9, local routing is performed on the data transmitted from UE100-1 and the data is transferred to UE100-2. For example, gNB200 sets a DRB for local routing for UE100-2 (steps S15 and S16). As a result, for example, not only is data transmitted from UE100-1 transferred to UE100-2, but data transmitted from UE100-2 can also be transferred to UE100-1. That is, UE100-1 and UE100-2 can transmit and receive data to each other via gNB200 without going through the core network.

[0076] In step S20, when the RAN identification information of the UE 100-2 itself is changed, the UE 100-2 may transmit new RAN identification information after the change to the UE 100-1.

[0077] Here, the case where the RAN identification information is changed is, for example, when the UE 100-2 moves and the cell ID of the connection destination is changed. Also, in step S20, the UE 100-2 transmits new RAN identification information to the UE 100-1, but may transmit new RAN identification information to the destination gNB. In this case, the UE 100-2 may transmit information indicating that there is a DRB for local routing to the destination gNB. When the UE 100-2 transmits new RAN identification information to the destination gNB, the destination gNB may transmit new RAN identification information to the source gNB 200.

[0078] In step S21, UE100-1 may transmit new RAN identification information of UE100-2 to gNB200.

[0079] (Modification of First Embodiment) Next, a modification of the first embodiment will be described.

[0080] In the first embodiment, it has been described that the UE 100-1 is in a discovery state (step S10) in which the UE 100-2 has been discovered. For example, although the UE 100-1 has discovered the UE 100-2, the UE 100-2 may move and become unable to discover the UE 100-2. In this case, the UE 100-1 may transmit information indicating that the UE 100-2 cannot be discovered to the gNB 200. The information may be a request to remove the DRB for local routing set from the gNB 200. In response to receiving the information, the gNB 200 removes the DRB for local routing set for the UE 100-1, and, if possible, also removes the DRB for local routing set for the UE 100-2.

[0081] In the first embodiment, the gNB 200 has been described as performing local routing. Instead of the gNB 200, the UE 100-3 may perform local routing. In this case, the UE 100-3 functions as a relay UE between the two UEs 100-1 and 100-2 and the gNB 200. Similar to the gNB 200 of the first embodiment, when the relay UE 100-3 receives the RAN identification information of the UE 100-2 from the UE 100-1, it sets a DRB for local routing for the UE 100-1. Furthermore, when the relay UE 100-3 receives the RAN identification information of the UE 100-1 from the UE 100-2, it sets a DRB for local routing for the UE 100-2. Then, the relay UE 100-3 can use these DRBs to transfer data transmitted from the UE 100-1 to the UE 100-2 and data transmitted from the UE 100-2 to the UE 100-2, respectively, without transferring the data to the gNB 200. In this case, the DRB may be a SL-DRB (Side Link DRB). In addition, the RAN identification information may be a Destination Layer-2 ID and / or a Source Layer-2 ID.

[0082] Second Embodiment Next, a second embodiment will be described.

[0083] In the first embodiment, an example in which RAN identification information is used has been described. In the second embodiment, an example in which a discovery identifier is used instead of RAN identification information is described.

[0084] Specifically, first, the first user equipment (e.g., UE 100-1) transmits to the base station (e.g., gNB 200) the discovery identifier of the second user equipment acquired when discovering the second user equipment (e.g., UE 100-2). Second, in response to receiving the discovery identifier, the base station inquires of the user equipment subordinate to the base station whether or not the user equipment has the discovery identifier. Third, the second user equipment responds to the inquiry. Fourth, in response to the response, the base station sets a first data radio bearer for the first user equipment and sets a second data radio bearer for the second user equipment. Fifth, the base station forwards the data received from the first user equipment using the first data radio bearer to the second user equipment using the second data radio bearer without forwarding the data to the core network.

[0085] In this way, the gNB 200 uses the discovery identifier to find the UE 100-2 discovered by the UE 100-1, and sets a DRB for local routing for the UE 100-1, thereby performing local routing. As a result, in the second embodiment, as in the first embodiment, the gNB 200 can appropriately perform local routing by Layer 2.

[0086] FIG. 10 is a diagram illustrating an example of operation according to the second embodiment.

[0087] As shown in FIG. 10 , in step S30, the UE 100-1 discovers the UE 100-2 by using a discovery function. The discovery function may be a function that uses direct discovery of proximity service communication, as in the first embodiment. The discovery function may be a function that uses a higher layer (for example, Open Connectivity Foundation). The UE 100-1 may decide to communicate with the UE 100-2 instead of or together with the discovery.

[0088] In step S31, the UE 100-1 notifies the access stratum (AS) of a discovery identifier. For example, an upper layer (for example, an application layer) of the UE 100-1 executes a discovery function to acquire the discovery identifier of the UE 100-2.

[0089] Here, the discovery identifier functions as an identifier for identifying a UE when the UE 100-1 discovers the other party UE 100-2 by executing a discovery function. The discovery identifier of the UE 100-2 can be an identifier for the UE 100-1 to identify a UE to which data is transmitted. Furthermore, the discovery identifier of the UE 100-1 can be an identifier for identifying a UE from which data is transmitted. The UE 100-1 may acquire the discovery identifier of the UE 100-2 from the UE 100-2 by discovering the UE 100-2. Furthermore, the UE 100-2 may also acquire the discovery identifier of the UE 100-2 from the UE 100-1 by the discovery.

[0090] In step S32, the UE 100-1 transmits a discovery identifier to the gNB 200. The discovery identifier to be transmitted includes the discovery identifier of the UE 100-2. The discovery identifier to be transmitted may include the discovery identifier of the UE 100-1.

[0091] In step S33, in response to receiving the discovery identifier, the gNB 200 inquires of the subordinate UE whether or not it has the discovery identifier of the UE 100-2. In this case, the gNB 200 may request other gNBs to inquire of whether or not it has the discovery identifier of the UE 100-2. The gNB 200 may make the inquiry by broadcasting a SIB (System Information Block) message including the discovery identifier of the UE 100-2.

[0092] In step S34, the UE 100-2 responds to the inquiry. Since the UE 100-2 belongs to the gNB 200, the UE 100-2 responds to the inquiry from the gNB 200. For example, the UE 100-2 may respond by transmitting an RRC message to the gNB 200 as a response message. If the UE 100-2 belongs to another gNB, the other gNB may transmit to the gNB 200 information indicating that the UE 100-2 is present in the gNB 200.

[0093] In step S35, the gNB 200 configures a DRB for local routing for the UE 100-1. The DRB, like the DRB of the first embodiment (step S14 of FIG. 10), may be used when the UE 100-1 transmits data addressed to the UE 100-2, or may be used when the UE 100-1 receives data addressed to itself transmitted from the UE 100-2. The UE 100-1 transmits the data by mapping the data addressed to the UE 100-2 to the DRB. Furthermore, the DRB may be associated with the discovery identifier of the UE 100-2 as restriction information.

[0094] In step S36, the gNB 200 configures a DRB for local routing for the UE 100-2. In this case, as in the first embodiment, the gNB 200 associates the DRB for local routing configured for the UE 100-1 with the DRB for local routing configured for the UE 100-2, and performs routing as a communication path.

[0095] In step S37, UE100-1 transmits data addressed to UE100-2 to gNB200 using a DRB for local routing.

[0096] In step S38, the gNB 200 receives data addressed to the UE 100-2 transmitted using the DRB, and forwards the received data to the UE 100-2 without forwarding it to the core network. The gNB 200 forwards the received data to the UE 100-2 using the DRB for local routing set for the UE 100-1 (step S35) and the DRB for local routing set for the UE 100-2 (step S36). In this case, the gNB 200 can forward the data transmitted from the UE 100-1 to the UE 100-2 because the DRB set for the UE 100-1 (step S35) and the DRB set for the UE 100-2 (step S36) are linked.

[0097] As in the first embodiment, gNB200 may configure a DRB for local routing for UE100-2 (step S36), thereby enabling not only data transfer from UE100-1 to UE100-2, but also data transfer from UE100-2 to UE100-1.

[0098] Third Embodiment Next, a third embodiment will be described.

[0099] The third embodiment is an example in which AMF301 notifies gNB200 that UE100-1 and UE100-2 are a pair of P2P (Peer to Peer) communication. Here, P2P communication means that UE100-1 and UE100-2 communicate via gNB200 without going through the core network. In the third embodiment, P2P communication and local routing may be used without distinction.

[0100] Specifically, first, a core network device (e.g., AMF301) connected to a core network transmits pairing information indicating that a first user apparatus (e.g., UE100-1) and a second user apparatus (e.g., UE100-2) are a pair that communicate via a base station without going through a core network to a base station (e.g., gNB200). Second, the base station sets a first data radio bearer in response to receiving the pairing information and the second identification information (e.g., RAN identification information of the UE100-2).

[0101] This allows the gNB200 to know that there is a pair performing P2P communication. Then, the gNB200 can configure the local routing described in the first embodiment for the pair.

[0102] FIG. 11 is a diagram illustrating an example of operation according to the third embodiment.

[0103] 11 , in step S40, the UE 100-1 may discover the UE 100-2 by using a discovery function. The discovery function may be a function that uses direct discovery of proximity service communication, as in the first embodiment, or may be a function that uses the Open Connectivity Foundation. When the UE 100-1 discovers the UE 100-2, the UE 100-1 may decide to perform P2P communication with the UE 100-2.

[0104] In step S41, the UE 100-1 transmits information indicating that P2P communication will be performed with the UE 100-2 to the AMF 301. The UE 100-1 may transmit the information by transmitting a NAS message including the information. The information may be the RAN identification information.

[0105] In step S42, the AMF 301 transmits pairing information to the gNB 200. The pairing information is information indicating that the UE 100-1 and the UE 100-2 are a pair that performs P2P communication via the gNB 200 without going through a core network. The AMF 301 may transmit the information by transmitting an NG message including the pairing information. The information may be a request to establish a communication path for P2P communication. The pairing information may include the RAN identification information.

[0106] In step S43, the gNB 200 and the UEs 100-1 and 100-2 perform processing to establish P2P communication. The processing to establish P2P communication may be the processing of steps S10 to S21 of the first embodiment. In this case, the gNB 200 receives the RAN identification information of the UE 100-2 from the UE 100-1, and when it further receives pairing information from the AMF 301, it may configure a DRB for local routing for the UE 100-1 (step S14). Also, the processing to establish P2P communication may be the processing of steps S30 to S38 of the second embodiment. In this case, the gNB 200 receives a response from the UE 100-2 (step S34), and when it further receives pairing information from the AMF 301, it may configure a DRB for local routing for the UE 100-1 (step S35).

[0107] Fourth Embodiment Next, a fourth embodiment will be described.

[0108] In the first to third embodiments, an example in which local routing is performed in the gNB 200 has been described. In this case, the data does not reach the UPF 302. Therefore, in the cellular communication system 1, it may not be possible to obtain the amount of data (or communication volume) for each user. Therefore, in the fourth embodiment, the gNB 200 records the amount of data transferred by local routing and transmits the recorded amount of data to the core network.

[0109] Specifically, first, a base station (e.g., gNB200) transfers data received from a first user apparatus (e.g., UE100-1) using a data radio bearer to a second user apparatus (e.g., UE100-2) without transferring the data to a core network. Second, the base station transmits the amount of data to a core network (e.g., AMF301).

[0110] This allows the core network to grasp the amount of data transferred by local routing at gNB200, enabling appropriate charging (or billing processing).

[0111] FIG. 12 is a diagram illustrating an example of operation according to the fourth embodiment.

[0112] As shown in FIG. 12, in step S50, UE100-1 transmits data addressed to UE100-2 to gNB200.

[0113] In step S51, gNB200 forwards data addressed to UE100-2 to UE100-2 by local routing without forwarding it to the core network.

[0114] In step S52, the gNB200 records the amount of data transferred (step S51) in memory. The gNB200 may record the amount of data in the payload portion of the SDAP SDU. The gNB200 may also record the amount of data in the payload portion of the PDCP SDU. The gNB200 may record the amount of data for each UE100. The gNB200 may only record the amount of data transmitted wirelessly using the licensed band. In this case, no charges are incurred for data transmitted wirelessly using the unlicensed band.

[0115] In step S53, the gNB 200 transmits the recorded data amount to the core network. In Figure 12, an example of the core network is shown as AMF 301.

[0116] [Other embodiments] A program that causes a computer to execute each process performed by the UE 100 or the gNB 200 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-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.

[0117] In addition, circuits that perform each process performed by UE100 or gNB200 may be integrated, and at least a portion of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC).

[0118] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "at least in part on." Furthermore, "obtain" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may also mean including only the listed items or including additional items in addition to the listed items. Furthermore, as used in this disclosure, the term "or" is not intended to mean an exclusive or. Furthermore, any reference to an element using a designation such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, reference to a first and a second element does not imply that only two elements may be employed therein, or that the first element must precede the second element in some way. In this disclosure, when articles are added by translation, such as a, an, and the in English, these articles are intended to include the plural unless the context clearly indicates otherwise.

[0119] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes can be made without departing from the scope of the invention. Furthermore, it is also possible to combine all or part of each embodiment within a consistent range.

[0120] This application claims priority to Japanese Patent Application No. 2021-118338 (filed July 16, 2021), the entire contents of which are incorporated herein by reference.

[0121] 1: Mobile communication system 10: 5GC 100 (100-1, 100-2): UE 110: Wireless communication unit 120: Control unit 200 (200-1 to 200-3): gNB 210: Wireless communication unit 220: Network communication unit 230: Control unit 301: AMF 302: UPF

Claims

1. A communication control method comprising: a first user device and a second user device being in a mutual discovery state, acquiring second identification information identifying the second user device, and the second user device acquiring first identification information identifying the first user device; the first user device transmitting the second identification information to a communication device, and the second user device transmitting the first identification information to the communication device; the communication device establishing a first data radio bearer for the first user device in response to receiving the second identification information, and establishing a second data radio bearer for the second user device in response to receiving the first identification information; and the communication device forwarding first data received from the first user device using the first data radio bearer to the second user device using the second data radio bearer without forwarding the data to a core network.

2. The communication control method according to claim 1, wherein the communication device is a base station, the first user device is connected to the base station, and the core network is connected to the base station.

3. The communication control method according to claim 1, wherein the communication device is a third user device.

4. The communication control method according to claim 1, wherein the forwarding includes the communication device forwarding second data received from the second user device using the second data radio bearer to the first user device using the first data radio bearer without forwarding the second data to the core network.

5. The communication control method according to claim 2, further comprising a core network device connected to the core network transmitting pairing information to the base station indicating that the first user equipment and the second user equipment are a pair that communicate via the base station without going through the core network, and wherein the setting includes setting the first data radio bearer by the base station in response to receiving the pairing information and the second identification information.

6. A communication control method comprising: a first user equipment transmitting to a base station a discovery identifier of the second user equipment acquired when the first user equipment discovered the second user equipment; the base station, in response to receiving the discovery identifier, inquiring of user equipment subordinate to the base station as to whether the user equipment has the discovery identifier; the second user equipment responding to the inquiry; the base station, in response to the response, establishing a first data radio bearer for the first user equipment and establishing a second data radio bearer for the second user equipment; and the base station forwarding first data received from the first user equipment using the first data radio bearer to the second user equipment using the second data radio bearer without forwarding the data to a core network.

7. The communication control method according to claim 6, wherein the forwarding includes the base station forwarding the second data received from the second user equipment using the second data radio bearer to the first user equipment using the first data radio bearer without forwarding the second data to the core network.

8. A communication control method comprising: a base station forwarding data received from the first user equipment using a data radio bearer to a second user equipment without forwarding the data to a core network; and the base station transmitting the amount of the data to the core network.

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