Communication Control Method

Abstract

To provide a communication control method, a relay node, a program, and a chip set that establish a packet data convergence protocol (PDCP) link between user equipment and user equipment and use the PDCP link via the relay node.SOLUTION: In a cellular communication system, a relay node (IAB (Integrated Access and Backhaul) node) having a function of user equipment relays data between first user equipment UE#1 and second user equipment UE#2. The relaying includes the relay node determining an egress radio link control (RLC) channel based on identification information related to communication between the first user equipment and the second user equipment and the egress RLC channel, and performing the relaying by Layer 2 relay using the egress RLC channel.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] The Third Generation Partnership Project (3GPP) (registered trademark; the same applies hereinafter), a standardization project for cellular communication systems, is considering the introduction of a new relay node called an Integrated Access and Backhaul (IAB) node (see, for example, "3GPP TS 38.300 V16.5.0 (2021-03)"). One or more relay nodes intervene in communication between a base station and a user device and relay this communication. Summary of the Invention

[0003] A communication control method according to a first aspect is a communication control method used in a cellular communication system. The communication control method includes a donor node configuring a first user equipment and a second user equipment to establish a data radio bearer (DRB) between the first user equipment and the second user equipment, respectively. The communication control method also includes the first user equipment and the second user equipment receiving the configuration and establishing a first PDCP (Packet Data Convergence Protocol) entity and a second PDCP entity, respectively. The communication control method further includes the first PDCP entity transmitting data to the second PDCP entity without going through a User Plane Function (UPF), and a relay node relaying the data by Layer 2 relaying, which is a layer lower than the PDCP layer.

[0004] A communication control method according to a second aspect is a communication control method for use in a cellular communication system. The communication control method includes a donor node configuring a routing setting for a relay node that performs local routing. The communication control method also includes the relay node transmitting data transmitted from a first user device to a second user device in accordance with the routing setting without going through a UPF.

[0005] A communication control method according to a third aspect is a communication control method for use in a cellular communication system. The communication control method includes a relay node transmitting data transmitted from a first user device to a second user device in accordance with a routing configuration without going through a UPF. The communication control method also includes the relay node transmitting a data amount of the data to a donor node. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a cellular communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating the relationship between IAB nodes, parent nodes, and child nodes according to one embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example configuration of a gNB (donor node) according to one embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of an IAB node (relay node) according to an embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of a UE (user equipment) according to an embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a protocol stack related to a Radio Resource Control (RRC) connection and a Non-Access Stratum (NAS) connection of an IAB-MT according to one embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of a protocol stack for the F1-U protocol according to one embodiment. [Figure 8]FIG. 8 is a diagram illustrating an example of a protocol stack for the F1-C protocol according to one embodiment. [Figure 9] 9A and 9B are diagrams illustrating an example of a PDCP link according to the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of operation according to the first embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of operation according to the second embodiment. [Figure 12] 12A and 12B are diagrams showing examples of relationships between IAB nodes in the second embodiment. [Figure 13] 13A and 13B are diagrams illustrating an example of RLC (Radio Link Control) channel information according to the second embodiment. [Figure 14] FIG. 14 is a diagram illustrating an example of operation according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] 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.

[0008] (Configuration of a cellular communication system) First, a configuration example 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. Specifically, the radio access method in the cellular communication system is NR (New Radio), which is a 5G radio access method. However, LTE (Long Term Evolution) may be applied at least partially to the cellular communication system. Furthermore, future cellular communication systems such as 6G may also be applied to the cellular communication system.

[0009] FIG. 1 is a diagram illustrating an example of the configuration of a cellular communication system 1 according to an embodiment.

[0010] 1, the cellular communication system 1 includes a 5G core network (5GC) 10, user equipment (UE) 100, base station devices (hereinafter sometimes referred to as "base stations") 200-1 and 200-2, and IAB nodes 300-1 and 300-2. The base station 200 may be referred to as a next generation Node B (gNB).

[0011] In the following, an example in which base station 200 is an NR base station will be mainly described, but base station 200 may also be an LTE base station (i.e., an evolved Node B (eNB)).

[0012] In the following, the base stations 200-1 and 200-2 may be referred to as gNB 200 (or base station 200), and the IAB nodes 300-1 and 300-2 may be referred to as IAB node 300.

[0013] The 5GC 10 has an AMF (Access and Mobility Management Function) 11, a UPF (User Plane Function) 12, and an SMF (Session Management Function) 13. The AMF 11 is a device that performs various mobility controls for the UE 100. The AMF 11 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 12 is a device that performs transfer control of user data, etc. The SMF 13 is a device that performs session management for the UE 100 and control of the UPF 12, etc.

[0014] Each gNB 200 is a fixed wireless communication node that manages one or more cells. The term cell is used to indicate the smallest unit of a wireless communication area. The term cell may also be used to indicate a function or resource for performing wireless communication with the UE 100. The term cell may also be used without distinction from a base station, such as the gNB 200. One cell belongs to one carrier frequency.

[0015] Each gNB 200 is interconnected with the 5GC 10 via an interface called an NG interface. Figure 1 illustrates two gNBs, gNB 200-1 and gNB 200-2, connected to the 5GC 10.

[0016] Each gNB 200 may be divided into a central unit (CU) and distributed units (DU). The CU and DU are connected to each other via an interface called an F1 interface. The F1 protocol is a communication protocol between the CU and DU, and includes an F1-C protocol, which is a control plane protocol, and an F1-U protocol, which is a user plane protocol.

[0017] The cellular communication system 1 supports IAB, which enables wireless relay of NR access using NR (New Radio) for backhaul. The donor gNB (or donor node, hereinafter sometimes referred to as the "donor node") 200-1 is the terminal node of the NR backhaul on the network side and is a donor base station with additional functions to support IAB. The backhaul can be multi-hopped via multiple hops (i.e., multiple IAB nodes 300).

[0018] FIG. 1 shows an example in which IAB node 300-1 wirelessly connects to donor node 200-1, IAB node 300-2 wirelessly connects to IAB node 300-1, and the F1 protocol is transmitted over two backhaul links.

[0019] The UE 100 is a mobile wireless communication device that performs wireless communication with a cell. The UE 100 may be any device that performs wireless communication with the gNB 200 or the IAB node 300. For example, the UE 100 may be a mobile phone terminal or a tablet terminal, a laptop computer, a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle, or an unmanned aerial vehicle or a device provided in an unmanned aerial vehicle. The UE 100 wirelessly connects to the IAB node 300 or the gNB 200 via an access link. FIG. 1 shows an example in which the UE 100 is wirelessly connected to the IAB node 300-2. The UE 100 indirectly communicates with the donor node 200-1 via the IAB node 300-2 and the IAB node 300-1. FIG. 1 shows an example in which the IAB node 300-2 and the IAB node 300-1 serve as relay nodes.

[0020] FIG. 2 is a diagram showing the relationship between an IAB node 300 and its parent nodes and child nodes.

[0021] As shown in FIG. 2, each IAB node 300 has an IAB-DU corresponding to a base station function unit and an IAB-MT (Mobile Termination) corresponding to a user equipment function unit.

[0022] An adjacent node (i.e., an upper node) on the NR Uu radio interface of the IAB-MT is called a parent node. The parent node is the DU of the parent IAB node or the donor node 200. The radio link between the IAB-MT and the parent node is called a backhaul link (BH link). FIG. 2 shows an example in which the parent nodes of the IAB node 300 are IAB nodes 300-P1 and 300-P2. The direction toward the parent node is called upstream. From the perspective of the UE 100, the upper node of the UE 100 may correspond to the parent node.

[0023] Adjacent nodes (i.e., lower nodes) on the NR access interface of the IAB-DU are called child nodes. The IAB-DU manages a cell, similar to the gNB 200. The IAB-DU terminates the NR Uu radio interface to the UE 100 and lower IAB nodes. The IAB-DU supports the F1 protocol to the CU of the donor node 200-1. While FIG. 2 shows an example in which the child nodes of the IAB node 300 are IAB nodes 300-C1 to 300-C3, the child nodes of the IAB node 300 may also include the UE 100. The direction toward the child nodes is called downstream.

[0024] Furthermore, all IAB nodes 300 connected to the donor node 200 via one or more hops form a directed acyclic graph (DAG) topology (hereinafter, sometimes referred to as "topology") with the donor node 200 as the root. In this topology, as shown in FIG. 2, adjacent nodes on the IAB-DU interface are child nodes, and adjacent nodes on the IAB-MT interface are parent nodes. The donor node 200 centrally manages, for example, resources, topology, and route management of the IAB topology. The donor node 200 is a gNB that provides network access to the UE 100 via a network of backhaul links and access links.

[0025] (Base station configuration) Next, the configuration of the gNB 200, which is a base station according to the embodiment, will be described. Fig. 3 is a diagram illustrating an example configuration of the gNB 200. As shown in Fig. 3, the gNB 200 has a radio communication unit 210, a network communication unit 220, and a control unit 230.

[0026] The wireless communication unit 210 performs wireless communication with the UE 100 and wireless communication with the IAB node 300. The wireless communication unit 210 has a receiving unit 211 and a transmitting unit 212. The receiving unit 211 performs various types of reception under the control of the control unit 230. The receiving unit 211 includes an antenna, and converts (down-converts) a wireless signal received by the antenna into a baseband signal (received signal), and outputs the signal to the control unit 230. The transmitting unit 212 performs various types of transmission under the control of the control unit 230. The transmitting unit 212 includes an antenna, and converts (up-converts) a baseband signal (transmitted signal) output by the control unit 230 into a wireless signal, and transmits the signal from the antenna.

[0027] The network communication unit 220 performs wired communication (or wireless communication) with the 5GC10 and wired communication (or wireless communication) with other adjacent gNBs 200. The network communication unit 220 has a receiving unit 221 and a transmitting unit 222. The receiving unit 221 performs various types of reception under the control of the control unit 230. The receiving unit 221 receives a signal from the outside and outputs the received signal to the control unit 230. The transmitting unit 222 performs various types of transmission under the control of the control unit 230. The transmitting unit 222 transmits the transmission signal output by the control unit 230 to the outside.

[0028] The control unit 230 performs various controls in the gNB 200. The control unit 230 includes at least one memory and at least one processor electrically connected to the memory. 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 processor performs processing of each layer, which will be described later. Furthermore, the control unit 230 may perform various processes in the gNB 200 (or the donor node 200) in each of the embodiments described below.

[0029] (Relay node configuration) Next, the configuration of the IAB node 300, which is a relay node (or relay node device, hereinafter sometimes referred to as a "relay node") according to the embodiment, will be described. FIG. 4 is a diagram showing an example configuration of the IAB node 300. As shown in FIG. 4, the IAB node 300 has a wireless communication unit 310 and a control unit 320. The IAB node 300 may have multiple wireless communication units 310.

[0030] The wireless communication unit 310 performs wireless communication (BH link) with the gNB 200 and wireless communication (access link) with the UE 100. The wireless communication unit 310 for BH link communication and the wireless communication unit 310 for access link communication may be provided separately.

[0031] The wireless communication unit 310 has a receiving unit 311 and a transmitting unit 312. The receiving unit 311 performs various types of reception under the control of the control unit 320. The receiving unit 311 includes an antenna, and converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the signal to the control unit 320. The transmitting unit 312 performs various types of transmission under the control of the control unit 320. The transmitting unit 312 includes an antenna, and converts (up-converts) a baseband signal (transmitted signal) output by the control unit 320 into a radio signal, and transmits the signal from the antenna.

[0032] The control unit 320 performs various controls in the IAB node 300. The control unit 320 includes at least one memory and at least one processor electrically connected to the memory. 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 and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes. The processor performs processing of each layer, which will be described later. Furthermore, the control unit 320 may perform various processes in the IAB node 300 in each of the embodiments described below.

[0033] (Configuration of user device) Next, a configuration of the UE 100, which is a user equipment according to the embodiment, will be described. Fig. 5 is a diagram illustrating an example of the configuration of the UE 100. As shown in Fig. 5, the UE 100 includes a radio communication unit 110 and a control unit 120.

[0034] The radio communication unit 110 performs radio communication in the access link, i.e., radio communication with the gNB 200 and radio communication with the IAB node 300. The radio communication unit 110 may also perform radio communication in the side link, i.e., radio communication with another UE 100. The radio communication unit 110 has a receiving unit 111 and a transmitting unit 112. The receiving unit 111 performs various receptions under the control of the control unit 120. The receiving unit 111 includes an antenna, and converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the signal to the control unit 120. The transmitting unit 112 performs various transmissions under the control of the control unit 120. The transmitting unit 112 includes an antenna, and converts (up-converts) a baseband signal (transmitted signal) output by the control unit 120 into a radio signal, and transmits the signal from the antenna.

[0035] The control unit 120 performs various controls in the UE 100. The control unit 120 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used in 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. The CPU executes programs stored in the memory to perform various processing. The processor performs processing of each layer, which will be described later. Furthermore, the control unit 120 may perform each processing in the UE 100 in each of the embodiments shown below.

[0036] (Protocol stack configuration) Next, the configuration of a protocol stack according to the embodiment will be described. Fig. 6 is a diagram illustrating an example of a protocol stack related to an RRC connection and a NAS connection of an IAB-MT.

[0037] As shown in FIG. 6, the IAB-MT of IAB node 300-2 has a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a non-access stratum (NAS) layer.

[0038] 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 IAB-MT of IAB node 300-2 and the PHY layer of the IAB-DU of IAB node 300-1 via a physical channel.

[0039] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the IAB-MT in IAB node 300-2 and the MAC layer of the IAB-DU in IAB node 300-1 via a transport channel. The MAC layer of the IAB-DU includes a scheduler, which determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the allocated resource blocks.

[0040] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the IAB-MT of IAB node 300-2 and the RLC layer of the IAB-DU of IAB node 300-1 via logical channels.

[0041] The PDCP layer performs header compression / decompression and encryption / decryption. Data and control information are transmitted between the PDCP layer of the IAB-MT of the IAB node 300-2 and the PDCP layer of the CU of the donor node 200 via a radio bearer.

[0042] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the IAB-MT of the IAB node 300-2 and the RRC layer of the CU of the donor node 200. When there is an RRC connection with the donor node 200, the IAB-MT is in an RRC connected state. When there is no RRC connection with the donor node 200, the IAB-MT is in an RRC idle state.

[0043] The NAS layer, which is positioned above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the IAB-MT of the IAB node 300-2 and the NAS layer of the AMF 11.

[0044] Figure 7 is a diagram showing a protocol stack for the F1-U protocol. Figure 8 is a diagram showing a protocol stack for the F1-C protocol. Here, an example is shown in which the donor node 200 is divided into a CU and a DU.

[0045] As shown in Figure 7, the IAB-MT of IAB node 300-2, the IAB-DU of IAB node 300-1, the IAB-MT of IAB node 300-1, and the DU of donor node 200 each have a BAP (Backhaul Adaptation Protocol) layer above the RLC layer. The BAP layer is a layer that performs routing processing and bearer mapping / demapping processing. In the backhaul, the IP layer is transmitted via the BAP layer, enabling routing over multiple hops.

[0046] In each backhaul link, PDUs (Protocol Data Units) of the BAP layer are transmitted via a backhaul RLC channel (BH NR RLC channel). Configuring multiple backhaul RLC channels in each BH link enables traffic prioritization and Quality of Service (QoS) control. The association between BAP PDUs and backhaul RLC channels is performed by the BAP layer of each IAB node 300 and the BAP layer of the donor node 200.

[0047] Note that the CU of the donor node 200 is a gNB-CU function of the donor node 200 that terminates the F1 interface to the IAB node 300 and the DU of the donor node 200. Also, the DU of the donor node 200 is a gNB-DU function of the donor node 200 that hosts the IAB BAP sublayer and provides wireless backhaul to the IAB node 300.

[0048] As shown in FIG. 8, the protocol stack of the F1-C protocol has an F1AP layer and an SCTP layer instead of the GTP-U layer and UDP layer shown in FIG.

[0049] In the following, the processing or operations performed by the IAB-DU and IAB-MT of the IAB may be simply referred to as the processing or operations of the "IAB." For example, the transmission of a BAP layer message from the IAB-DU of IAB node 300-1 to the IAB-MT of IAB node 300-2 will be described as the IAB node 300-1 sending the message to IAB node 300-2. In addition, the processing or operations of the DU or CU of the donor node 200 may be simply referred to as the processing or operations of the "donor node."

[0050] Also, the upstream direction and the uplink (UL) direction may be used interchangeably, and the downstream direction and the downlink (DL) direction may be used interchangeably.

[0051] [First embodiment] Next, a first embodiment will be described.

[0052] (Routing and local routing) First, routing will be described.

[0053] One of the functions of the BAP layer is the function of routing packets to the next hop. In a network formed by multiple IAB nodes 300, each IAB node 300 forwards a received packet to the next hop, ultimately causing the packet to be transmitted to the destination IAB node 300 (or donor node 200). Routing, for example, involves controlling to which IAB node 300 a received packet is forwarded. Such routing settings are performed by the donor node 200.

[0054] However, in a network configured with a plurality of IAB nodes 300, a line failure may occur in the backhaul link between the IAB nodes 300.

[0055] In a multi-hop network in which a packet is forwarded successively by a plurality of IAB nodes 300, the data packet can be forwarded to the destination IAB node 300 (or the donor node 200) via an alternative path. Forwarding a data packet using an alternative path in this manner may be referred to as local routing. Local routing may be performed by selecting an alternative path from alternative path candidates set by the donor node 200.

[0056] Furthermore, communications within a 3GPP system are typically routed through the core network (specifically, the UPF 12). When two UEs (e.g., UE #1 (100-1) and UE #2 (100-2)) communicate, even if these UEs are in a local area (e.g., within the coverage of the same IAB node 300), the data must first reach the UPF 12 and then return along the same route. In such cases, routing data without going through the core network (e.g., in the IAB node 300) can reduce the amount of traffic in the core network and delays that occur in communications within the core network. This type of routing that does not go through the core network is sometimes referred to as local routing.

[0057] (DRB establishment and PDCP entity establishment) Next, DRB establishment (Data Radio Bearer establishment) and PDCP entity establishment will be described.

[0058] The DRB and PDCP entities may be established when establishing a PDU session.

[0059] The PDU session is a logical path for transferring user data between the UE 100 and the UPF 12. After the UE 100 requests the network to establish a PDU session, the UE 100 receives an RRC Reconfiguration message from the gNB 200. The RRC Reconfiguration message includes radio bearer configuration information (radioBearerConfig) for configuring a DRB. Based on the radio bearer configuration information, the UE 100 establishes a DRB for a new PDU session and generates a mapping rule for mapping a Quality of Service Flow ID (QFI) to the DRB.

[0060] The radio bearer configuration information includes DRB identification information (DRB ID) and PDCP configuration information (PDCP Config). If the UE 100 confirms that the DRB ID is not part of the current configuration of the UE 100, the UE 100 establishes PDCP according to the received PDCP configuration information.

[0061] After the DRB and PDCP are established, user data is exchanged between the UE 100 and the gNB 200 on the DRB according to the mapping rule. Also, the user data is exchanged between the gNB 200 and the UPF 12 on the tunnel protocol of the PDU session.

[0062] In this way, the UE 100 can establish a DRB and a PDCP entity based on the radio bearer configuration information included in the RRC Reconfiguration message.

[0063] In the following, the establishment of a DRB and the establishment of a PDCP entity may be used interchangeably.

[0064] (PDCP link) The IAB node 300 performs Layer 2 relay. Specifically, it relays user data using layers (sublayers) below the RLC layer and the BAP layer, and does not use layers above these layers (specifically, the PDCP layer and SDAP layer). Therefore, no PDCP link exists between the IAB nodes 300.

[0065] 9(A) is a diagram showing an example of a PDCP link according to the first embodiment. As shown in FIG. 9(A), a PDCP link exists between the UE 100 and the CU of the donor node 200. However, for the reasons described above, no PDCP link exists between the UE 100 and the IAB node 300.

[0066] Therefore, even if the IAB node 300 transmits data (PDCP PDU) transmitted from the UE #1 (100-1) to the UE #2 (100-2) by local routing, the PDCP link is not established, and therefore the UE #2 (100-2) may not be able to decode the data. Specifically, the PDCP PDU encrypted by the UE #1 (100-1) may not be able to be decoded by the UE #2 (100-2).

[0067] Therefore, in the first embodiment, a PDCP link is established between the UEs 100, and data is exchanged using the PDCP link.

[0068] Specifically, first, a donor node (e.g., donor node 200) configures a first user equipment (e.g., UE #1 (100-1)) and a second user equipment (e.g., UE #2 (100-2)) to establish a data radio bearer (DRB) between the first user equipment and the second user equipment. Second, the first user equipment and the second user equipment receive the configuration and establish a first PDCP entity and a second PDCP entity, respectively. Third, the first PDCP entity transmits data to the second PDCP entity without going through a UPF (e.g., UPF 12).

[0069] As a result, a PDCP link is established between the UEs 100, and even if the IAB node 300 performs local routing on data transmitted from the UE #1 (100-1) and forwards the data to the UE #2 (100-2), the data can be efficiently acquired by the UE #2 (100-2). Furthermore, the local routing in the IAB node 300 allows the data transmitted from the UE #1 (100-1) to be forwarded to the UE #2 (100-2) without going through the core network (e.g., the UPF 12). This makes it possible to reduce the amount of traffic in the core network and to reduce delays that occur in communications within the core network.

[0070] (Operation example of the first embodiment) Fig. 10 is a diagram illustrating an example of operation according to the first embodiment. Note that the example of operation illustrated in Fig. 10 includes an example of establishing a PDCP link between UE #1 (100-1) and UE #2 (100-2).

[0071] As shown in FIG. 10, in step S10, the donor node 200 starts the process.

[0072] In step S11, the donor node 200 may obtain information about a PDU session that can be locally routed from a CN (Core Network). The CN may be at least one of the AMF 11, the UPF 12, and the SMF 13 included in the 5GC 10.

[0073] First, for example, when data transmitted from UE #1 (100-1) is returned by the UPF 12 and transmitted to UE #2 (100-2), the donor node 200 may acquire information about the PDU session. Specifically, this is the case when data transmitted from the donor node 200 via a GTP (General Packet Radio Service Tunneling Protocol) tunnel is returned by the UPF 12 and transmitted toward a different GTP tunnel of the same donor node 200.

[0074] Alternatively, for example, when the UPF 12 confirms that the IP address of the UE#2 (100-2) exists in the same network, the donor node 200 may obtain information about the PDU session.

[0075] Second, the information about the PDU session includes, for example, any of the following:

[0076] (A1) PDU session ID: PDU session ID between UE 100 and UPF 12. When there is a loopback at UPF 12 as described above, a pair of a PDU session ID between UE #1 (100-1) and UPF 12 and a PDU session ID between UPF 12 and UE #2 (100-2) may be information about the PDU session.

[0077] (A2) GTP tunnel ID: GTP tunnel ID between the donor node 200 and the UPF 12. When there is a loopback at the UPF 12 as described above, a pair of the GTP tunnel ID between the donor node 200 and the UPF 12 and the GTP tunnel ID between the UPF 12 and the donor node 200 may be information related to the PDU session.

[0078] (A3) QoS Flow ID (QFI)

[0079] (A4) IP address of UE 100: For example, a pair of the IP address of UE #1 (100-1) and the IP address of UE #2 (100-2) may be information about a PDU session.

[0080] (A5) UE-ID (e.g., NG-AP UE ID or 5G-S-TMSI (Temporary Mobile Subscriber Identity)): For example, a pair of UE-ID for UE #1 (100-1) and UE-ID for UE #2 (100-2) may be information about the PDU session.

[0081] The donor node 200 obtains information about the PDU session because this information may be used in establishing a DRB or in transferring data after the DRB is established.

[0082] In step S12, the donor node 200 decides to perform local routing.

[0083] In step S13, the donor node 200 performs settings for establishing a DRB for the UE #1 (100-1) and the UE #2 (100-2). For example, the donor node 200 performs settings for establishing a DRB by transmitting an RRC Reconfiguration message including the above-mentioned radio bearer setting information to the UE #1 (100-1) and the UE #2 (200-2).

[0084] In this case, the RRC Reconfiguration message may include information indicating that it is a DRB for P2P (Peer to Peer) between UEs. That is, the information is information indicating that it is PDCP establishment (DRB establishment) between UE #1 (100-1) and UE #2 (100-2) (for example, FIG. 9(B)), and not PDCP establishment (DRB establishment) between the donor node 200 and the UE 100 (for example, FIG. 9(A)). The information indicating that it is a DRB for P2P (Peer to Peer) between UEs may indicate that it is a target for local routing.

[0085] The RRC Reconfiguration message may also include information about the other party's UE 100. The information may include, for example, the IP address of the UE #2 (100-2) or the UE-ID of the UE #2 (100-2).

[0086] Furthermore, the RRC Reconfiguration message may include a target QoS flow ID.

[0087] Furthermore, the RRC Reconfiguration message may include information about the PDU session acquired by the donor node 200 in step S11.

[0088] In step S14, UE#1 (100-1) and UE#2 (100-2) receive the setting and establish a PDCP entity.

[0089] For example, UE#1 (100-1) and UE#2 (200-2) establish a PDCP entity based on radio bearer configuration information (radioBearerConfig) included in the RRC Reconfiguration message. UE#1 (100-1) and UE#2 (200-2) may also establish a PDCP entity based on information indicating a P2P DRB and the radio bearer configuration information included in the RRC Reconfiguration message. As a result, a PDCP entity is established between UE#1 (100-1) and UE#2 (100-2), as shown in FIG. 9(B).

[0090] Returning to FIG. 10, in step S15, UE #1 (100-1) outputs predetermined data to the PDCP entity (or DRB). The predetermined data is data that matches the IP address of UE #2. Or, the predetermined data is data that matches the target QoS flow ID. Or, the predetermined data is data that matches the target PDU session ID. For example, the RLC entity of UE #1 (100-1) outputs the predetermined data to the PDCP entity as data addressed to UE #2 (100-2). The PDCP entity of UE #1 (100-1) transmits the predetermined data to the PDCP entity of UE #2 (100-2). On the other hand, the RLC entity of UE #1 (100-1) transmits data that is not the predetermined data to the RLC entity of the IAB node 300 as data addressed to the donor node 200.

[0091] In step S16, UE #2 (100-2) receives the predetermined data via the IAB node 300 (or via the donor node 200). That is, the PDCP entity of UE #2 (100-2) receives the predetermined data (PDCP PDU) transmitted from the PDCP entity of UE #1 (100-1). Note that both UE #1 (100-1) and UE #2 (100-2) may use the security key used in the NR Uu radio interface as the PDCP security key.

[0092] In step S17, UE#1 (100-1) and UE#2 (100-2) end the series of processes.

[0093] [Second embodiment] Next, a second embodiment will be described.

[0094] In the first embodiment, an example has been described in which, after UE#1 (100-1) and UE# (100-2) establish a PDCP entity, the IAB node 300 performs local routing and transfers data.

[0095] The second embodiment is an embodiment of how the IAB node 300 performs local routing and transfers data.

[0096] Specifically, first, a donor node (e.g., donor node 200) performs routing configuration for a relay node (e.g., IAB node 300) that performs local routing. Second, the relay node transmits data transmitted from a first user device (e.g., UE#1 (100-1)) to a second user device (e.g., UE#2 (100-2)) in accordance with the routing configuration, without going through a UPF (e.g., UPF 12).

[0097] As a result, the IAB node 300 can properly transfer the data transmitted from the UE #1 (100-1) to the UE #2 (100-2) by local routing without going through the UPF 12.

[0098] Here, a general concrete example of routing based on routing settings will be described.

[0099] (Example of routing) In the IAB node 300, packet routing is performed, for example, as follows. That is, the IAB-CU of the donor node 200 provides routing configuration to the IAB-DU of each IAB node 300. The provided routing configuration includes a routing ID and a next-hop BAP address. The routing ID is composed of a (destination) BAP address and a path ID. When each IAB node 300 receives a packet (BAP packet), it reads the destination BAP address included in the header of the packet. Each IAB node 300 determines whether the destination BAP address matches the BAP address of its own IAB node 300. When the destination BAP address matches its own BAP address, each IAB node 300 determines that the data packet has reached its destination. On the other hand, when the destination BAP address does not match its own BAP address, each IAB node 300 forwards the packet to the IAB node 300 with the next-hop BAP address in accordance with the routing configuration. The routing configuration is performed, for example, by using an F1AP message.

[0100] In this way, each IAB node 300 forwards the received BAP packet to the next hop in accordance with the routing settings set by the donor node 200 .

[0101] In the second embodiment, the donor node 200 sets a new routing ID for the IAB node 300 that performs local routing, and also sets RLC channel information linked to the routing ID, thereby setting up local routing. This will be described in detail below.

[0102] (Operation example of the second embodiment) FIG. 11 is a diagram illustrating an example of operation according to the second embodiment.

[0103] As shown in FIG. 11, in step S20, the donor node 200 starts the process.

[0104] In step S21, the donor node 200 performs settings for establishing a DRB for UE #1 (100-1) and UE #2 (100-2). Step S21 is the same as step S13 (FIG. 10) in the first embodiment. Step S21 may be performed after step S23, which will be described later.

[0105] In step S22, the donor node 200 performs routing settings for the IAB node 300 that performs local routing.

[0106] First, the donor node 200 sets a new routing ID to the IAB node 300 that performs local routing. As described above, the routing ID includes a destination BAP address. The donor node 200 may specify the BAP address of the IAB node 300 that UE#1 accesses as the destination BAP address included in the new routing ID.

[0107] Fig. 12(A) is a diagram showing an example of the relationship between IAB nodes 300 according to the second embodiment. In the example of Fig. 12(A), UE#2 (100-2) is also accessing the IAB node 300 that is accessed by UE#1 (100-1). In such a case, local routing is performed in the IAB node 300. The donor node 200 may use the BAP address of the IAB node 300 as the destination BAP address.

[0108] Fig. 12(B) is a diagram showing an example of the relationship between IAB nodes 300 according to the second embodiment. In Fig. 12(B), UE#1 (100-1) accesses IAB node 300-1, and UE#2 (100-2) accesses IAB node 300-3. Furthermore, IAB node 300-2 is the parent node of the two IAB nodes 300-1 and 300-3.

[0109] The donor node 200 may select the IAB node 300-1, the IAB node 300-2, and / or the IAB node 300-3 as the IAB node 300 that performs local routing. However, the donor node 200 may specify the BAP address of the IAB node 300-3 as the destination BAP address of the new routing ID.

[0110] 12(B), the destination of the data (BAP PDU) to be locally routed is set to the BAP address of the IAB node 300-3 in the IAB node 300-1 and the IAB node 300-2. Therefore, the donor node 200 may transmit, to the IAB node 300-1 and the IAB node 300-2, information indicating that the destination included in the header of the BAP PDU to be locally routed is to be set to the BAP address of the IAB node 300-3.

[0111] Note that the new routing ID may be set by the CU of the donor node 200 transmitting an F1AP message including the routing ID to the IAB-DU of the IAB node 300. Also, the new routing ID may be set by the CU of the donor node 200 transmitting an RRC message including the routing ID to the IAB-MT of the IAB node 300.

[0112] Furthermore, information indicating that the destination included in the header of the BAP PDU to be locally routed is to be set to the BAP address of the IAB node 300-3 may also be transmitted by the F1AP message or the RRC message.

[0113] Second, the donor node 200 sets RLC Channel information associated with the new routing ID in the IAB node 300 that performs local routing.

[0114] Fig. 13(A) is a diagram illustrating an example of RLC channel information according to the second embodiment. In the example of Fig. 13(A), a prior-hop BAP address and a next-hop BAP address are included. Therefore, the RLC channel information illustrated in Fig. 13(A) may be set in, for example, the IAB node 300-2 in Fig. 12(B).

[0115] Figure 13(B) is also a diagram showing an example of RLC channel information according to the second embodiment. The RLC channel information shown in Figure 13(B) includes a routing ID. Therefore, the IAB node 300 can identify the next hop BAP address and the egress RLC CH ID from the routing ID.

[0116] However, Figures 13(A) and 13(B) are examples in which a BAP address is included in the RLC channel information. For example, in the IAB node 300 in Figure 12(A), a BAP header is not added to either the input or output side. Also, in the IAB node 300-1 in Figure 12(B), a BAP header is not added to the input side, and in the IAB node 300-3 in Figure 12(B), a BAP header is not added to the output side. Therefore, for example, local routing of a packet may be performed using an ingress RLC CH ID and / or an egress RLC CH ID instead of a BAP address (Prior-HOP BAP Address and Next-HOP BAP Address). RLC channel information that does not include a BAP address and includes an ingress RLC CH ID and / or an egress RLC CH ID may also be used.

[0117] The donor node 200 may also transmit to the IAB node 300 binding information that binds the new routing ID with the RLC channel information.

[0118] The RLC channel may be set up by the CU of the donor node 200 transmitting an F1AP message including RLC channel information to the IAB-DU of the IAB node 300. The CU of the donor node 200 may also transmit an F1AP message including binding information to the IAB-DU of the IAB node 300. The RLC channel may be set up and the binding information may be transmitted by an RRC message instead of an F1AP message.

[0119] 11, in step S23, the IAB node 300 performs local routing in accordance with the routing setting. The IAB node 300 (IAB node 300-2 in FIG. 12(B)) may rewrite the destination of the BAP PDU header to the BAP address of the IAB node 300-3 accessed by UE#2 (100-2). The IAB node 300 may also rewrite the path ID included in the routing ID. For each new routing ID, the donor node 200 may transmit the destination BAP address (or the entire routing ID) after local routing (or after rewriting) to the IAB node 300 that performs local routing.

[0120] Then, in step S24, the IAB node 300 ends the series of processes.

[0121] [Third embodiment] Next, a third embodiment will be described.

[0122] In the first and second embodiments, an example has been described in which the IAB node 300 performs local routing and transfers data from the UE #1 (100-1) to the UE #2 (100-2) without going through the UPF 12.

[0123] However, data is not transferred to the CN including the UPF 12. Therefore, the CN cannot grasp the amount of data transferred between the UE #1 (100-1) and the UE #2 (100-2).

[0124] Therefore, in the third embodiment, an example will be described in which, when data is forwarded by local routing, the IAB node 300 transmits the amount of the data to the donor node 200. Specifically, first, a relay node (e.g., the IAB node 300) transmits data transmitted from a first user device (e.g., UE#1 (100-1)) to a second user device (e.g., UE#2 (100-2)) in accordance with a routing setting without going through a UPF (e.g., UPF 12). Second, the relay node transmits the amount of the data to a donor node (e.g., the donor node 200).

[0125] (Operation example of the third embodiment) FIG. 14 is a diagram illustrating an example of operation according to the third embodiment.

[0126] As shown in FIG. 14, in step S30, the IAB node 300 starts the process.

[0127] In step S31, the IAB node 300 performs local routing. As in the first or second embodiment, for example, the IAB node 300 performs local routing on data transmitted from the UE #1 (100-1) and transmits the data to the UE #2 (100-2) without going through the UPF 12.

[0128] In step S32, the IAB node 300 counts the amount of data and stores (or records; hereinafter, this may be referred to as "storing") it in memory. The IAB node 300 may count the amount of data in the payload portion of the BAP PDU that has been locally routed and store it in memory. Alternatively, the IAB node 300 may count the amount of data in the entire BAP PDU, including the BAP header, and store it in memory.

[0129] The storage may be performed in the BAP layer. In this case, for example, the BAP layer counts the data amount of the BAP PDU, stores it in a memory, and outputs the stored data amount (cumulative total) to the RRC layer in response to a request from the RRC layer.

[0130] Alternatively, the storage may be performed in the RRC layer. In this case, for example, the RRC layer receives the amount of data counted for each BAP packet transfer from the BAP layer, and stores the cumulative total of the amount of data in memory.

[0131] In step S33, the IAB node 300 transmits the amount of data to the donor node 200. For example, the IAB node 300 reads out the amount of data stored in the memory and transmits it to the donor node 200.

[0132] First, the IAB node 300 may transmit at least one of the PDU session ID of the UE 100, the DRB ID of the UE 100, the routing ID, and the RLC Channel ID in association with the amount of data.

[0133] Second, the IAB node 300 may send time information along with the amount of data to the donor node 200. The time information may be a measurement time, a start time, an end time, or a combination thereof.

[0134] Third, the IAB node 300 may transmit the amount of data to the donor node 200 using the following as a trigger. That is, the IAB node 300 may transmit the amount of data in response to a request from the donor node 200. The IAB node 300 may also transmit the amount of data when the setting for performing local routing (for example, step S22 (FIG. 11) in the second embodiment) is removed. Furthermore, the IAB node 300 may transmit the amount of data when the amount of data reaches a threshold. The threshold may be set by the donor node 200. Furthermore, the IAB node 300 may transmit the amount of data periodically. The period (or time interval) may be set by the donor node 200.

[0135] The IAB-MT of the IAB node 300 may transmit an RRC message including the amount of data to the CU of the donor node 200. The IAB-DU of the IAB node 300 may transmit an F1AP message including the amount of data to the CU of the donor node 200.

[0136] In step S34, the donor node 200 may transmit the amount of data received from the IAB node 300 to the CN including the AMF 11. The CN may store the amount of data in a memory as the amount of data of the user. The CN performs charging or accounting processing based on the amount of data.

[0137] [Other embodiments] A program may be provided that causes a computer to execute each process performed by the UE 100, the gNB 200, or the IAB node 300. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed 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.

[0138] In addition, circuits that perform each process performed by UE100, gNB200, or IAB node 300 may be integrated, and at least a portion of UE100, gNB200, or IAB node 300 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0139] 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 elements using designations 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 first and second elements does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0140] 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.

[0141] This application claims priority to Japanese Patent Application No. 2021-115335 (filed July 12, 2021), the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0142] 1: Mobile communication system 10:5GC 11:AMF 12:UPF 13:SMF 100:UE 110: Wireless communication unit 120: Control unit 200 (200-1, 200-2): gNB (donor node) 210: Radio Communication Department 220: Network Communication Department 230: Control unit 300: IAB node 310: Radio Communication Department 320: Control unit

Claims

1. A communication control method for use in a cellular communication system, comprising: a relay node having a function of a user equipment relaying data between a first user equipment and a second user equipment; The relaying includes the relay node determining the outgoing RLC channel based on identification information related to the communication between the first user equipment and the second user equipment and the outgoing RLC channel, and performing the relaying by Layer 2 relay using the outgoing RLC channel. Communication control method.

2. a relay node having a function of a user equipment; a first user device; and a second user device, the relay node relays data between the first user device and the second user device; The relay node determines the outgoing RLC channel based on identification information regarding communication between the first user equipment and the second user equipment and the outgoing RLC channel, and performs the relaying by Layer 2 relay using the outgoing RLC channel. Cellular communication systems.

3. A relay node having a function of a user equipment in a cellular communication system, a control unit that relays data between a first user device and a second user device; The control unit includes a control unit that determines the outgoing RLC channel based on identification information related to communication between the first user equipment and the second user equipment and an outgoing RLC channel, and performs the relaying by Layer 2 relay using the outgoing RLC channel. Relay node.

4. A relay node having a function of a user equipment in a cellular communication system, Execute a process of relaying data between a first user device and a second user device; The relaying process includes determining the outgoing RLC channel based on identification information related to communication between the first user equipment and the second user equipment and an outgoing RLC channel, and performing the relaying by Layer 2 relay using the outgoing RLC channel. program.

5. A chipset for a relay node having a function of a user equipment in a cellular communication system, comprising: Relaying data between a first user device and a second user device; The relaying includes determining the outgoing RLC channel based on identification information related to communication between the first user equipment and the second user equipment and an outgoing RLC channel, and performing the relaying by Layer 2 relay using the outgoing RLC channel. Chipset.

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