Donor node, processor, communication method, communication system, and program

Abstract

To provide a donor node, a processor, a communication method, a communication system, and a program for use in a cellular communication system.SOLUTION: In a cellular communication system, a gNB 200-1, which is an IAB donor node having thereunder an IAB node 300 which is a relay node, sends a request message for migrating traffic of the relay node to between the donor node and another donor node 200-2 to the other node, and receives a response message to the request message from the other donor node. The request message includes information indicating a TNL (Transport Network Layer) address related to traffic migration.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a donor node, a processor, a communication method, a communication system, and a program for use in a cellular communication system. [Background technology]

[0002] In the cellular communication system standardization project 3GPP (Third Generation Partnership Project) (registered trademark, hereinafter the same), the introduction of a new relay node called an IAB (Integrated Access and Backhaul) node is being considered (see, for example, "3GPP TS 38.300 V16.2.0 (2020-07)"). One or more relay nodes are involved 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 first relay node under a first donor base station transmitting a first packet to a second donor base station different from the first donor base station. The communication control method also includes the second donor base station forwarding the first packet to the first donor base station using a path for data forwarding, and the first donor base station transmitting the packet to a network.

[0004] A communication control method according to a second aspect is a communication control method used in a cellular communication system. The communication control method includes a first relay node under a first donor base station inquiring of a second relay node under a second donor base station different from the first donor base station as to whether or not it has a path to the first donor base station. The communication control method also includes, when the second relay node has a path to the first donor base station, transmitting a response to the inquiry to the first relay node.

[0005] A communication control method according to a third aspect is a communication control method used in a cellular communication system. The communication control method includes a first user equipment function unit of a relay node, to which a first BAP address is set by a first donor base station, transmitting a second BAP address set by a second donor base station to a second user equipment function unit of the relay node, to the first donor base station. The communication control method also includes a second user equipment function unit transmitting the first BAP address to the second donor base station.

[0006] A communication control method according to a fourth aspect is a communication control method used in a cellular communication system. The communication control method includes a relay node having a first user equipment function unit, a first BAP address being set for the first user equipment function unit by a first donor base station, and the communication control method includes the relay node transmitting the second BAP address to the second donor base station when establishing a connection to a second donor base station. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a cellular communication system according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the relationship between IAB nodes, parent nodes, and child nodes. [Diagram 3] FIG. 3 is a diagram showing an example configuration of a gNB (base station) according to one embodiment. [Figure 4] FIG. 4 is a diagram illustrating a configuration example of an IAB node (relay node) according to an embodiment. [Diagram 5] FIG. 5 is a diagram illustrating a configuration example of a UE (user equipment) according to an embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a protocol stack related to an RRC connection and a NAS connection of an IAB-MT. [Figure 7]FIG. 7 is a diagram showing an example of a protocol stack related to the F1-U protocol. [Figure 8] FIG. 8 is a diagram showing an example of a protocol stack for the F1-C protocol. [Figure 9] FIG. 9 is a diagram showing an example of the configuration of the cellular communication system according to the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating an operation example of the first embodiment. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of a cellular communication system according to the third embodiment. [Figure 12] FIG. 12 is a diagram illustrating an operation example of the third embodiment. [Figure 13] FIG. 13 is a diagram showing an example of the configuration of a cellular communication system according to the fourth embodiment. [Figure 14] FIG. 14 is a diagram illustrating an operation example of the fourth embodiment. [Figure 15] FIG. 15 is a diagram illustrating an operation example of the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 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.

[0009] (Configuration of Cellular Communication System) A configuration example of a cellular communication system according to an embodiment will be described. The cellular communication system 1 according to an embodiment is a 3GPP 5G system. Specifically, the radio access method in the cellular communication system 1 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 1. Furthermore, the cellular communication system 1 may also be applied to future cellular communication systems such as 6G.

[0010] FIG. 1 is a diagram showing an example of the configuration of a cellular communication system 1 according to an embodiment.

[0011] As shown in Fig. 1, the cellular communication system 1 includes a 5G core network (5GC) 10, a user equipment (UE: User Equipment) 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 gNB.

[0012] 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 eNB).

[0013] 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.

[0014] The 5GC 10 has an Access and Mobility Management Function (AMF) 11 and a User Plane Function (UPF) 12. The AMF 11 is a device that performs various mobility controls for the UE 100. The AMF 11 manages information on the area in which the UE 100 is located by communicating with the UE 100 using Non-Access Stratum (NAS) signaling. The UPF 12 is a device that performs transfer control of user data.

[0015] Each gNB 200 is a fixed wireless communication node and manages one or more cells. A cell is used as a term indicating the smallest unit of a wireless communication area. A cell may be used as a term indicating a function or resource for performing wireless communication with a UE 100. One cell belongs to one carrier frequency. In the following, a cell and a base station may be used without distinction.

[0016] Each gNB 200 is mutually connected to the 5GC 10 via an interface called an NG interface. In FIG. 1, two gNBs 200-1 and 200-2 connected to the 5GC 10 are illustrated.

[0017] Each gNB 200 may be divided into a central unit (CU) and a distributed unit (DU). The CU and the DU are connected to each other via an interface called an F1 interface. The F1 protocol is a communication protocol between the CU and the DU, and includes an F1-C protocol, which is a control plane protocol, and an F1-U protocol, which is a user plane protocol.

[0018] The cellular communication system 1 supports IAB, which enables wireless relay of NR access using NR for backhaul. The donor gNB 200-1 is a 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).

[0019] FIG. 1 illustrates an example in which IAB node 300-1 wirelessly connects to donor gNB 200-1, IAB node 300-2 wirelessly connects to IAB node 300-1, and the F1 protocol is transmitted over two backhaul hops.

[0020] 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 is a mobile phone terminal, 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 aircraft or a device provided in an aircraft. 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 gNB 200-1 via the IAB node 300-2 and the IAB node 300-1.

[0021] FIG. 2 is a diagram showing the relationship between the IAB node 300, parent nodes, and child nodes.

[0022] 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.

[0023] 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 a parent IAB node or a DU of the donor gNB 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 300P1 and 300P2. 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.

[0024] Adjacent nodes (i.e., lower nodes) on the NR access interface of the IAB-DU are called child nodes. The IAB-DU manages cells, similar to the gNB 200. The IAB-DU terminates the NR Uu radio interface to the UE 100 and the lower IAB nodes. The IAB-DU supports the F1 protocol to the CU of the donor gNB 200-1. In FIG. 2, an example is shown in which the child nodes of the IAB node 300 are the IAB nodes 300C1-300C3, but the child nodes of the IAB node 300 may include the UE 100. The direction toward the child nodes is called downstream.

[0025] (Base station configuration) Next, a configuration of the gNB 200 which is a base station according to the embodiment will be described. Fig. 3 is a diagram showing an example of the configuration of the gNB 200. As shown in Fig. 3, the gNB 200 has a wireless 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 receptions 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 transmissions 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 receptions 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 transmissions 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 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 a baseband signal. 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 230 may perform each processing in the gNB 200 in each of the embodiments shown below.

[0029] (Configuration of relay node) 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 of the 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 receptions under the control of the control unit 320. The receiving unit 311 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 320. The transmitting unit 312 performs various transmissions 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 wireless 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 a program 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 a baseband signal. The CPU executes a program stored in the memory to perform various processing. The processor performs processing of each layer, which will be described later. The control unit 320 may also perform each processing in the IAB node 300 in each of the following embodiments.

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

[0034] The wireless communication unit 110 performs wireless communication in an access link, that is, wireless communication with the gNB 200 and wireless communication with the IAB node 300. The wireless communication unit 110 may also perform wireless communication in a side link, that is, wireless communication with another UE 100. The wireless 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 wireless 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 wireless 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 a program 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 a baseband signal. The CPU executes a program stored in the memory to perform various processing. The processor performs processing of each layer, which will be described later. The control unit 120 may also perform each processing in the UE 100 in each of the following embodiments.

[0036] (Protocol stack configuration) Next, a configuration of a protocol stack according to an embodiment will be described. Fig. 6 is a diagram showing 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 the IAB node 300-2 and the PHY layer of the IAB-DU of the 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 of IAB node 300-2 and the MAC layer of the IAB-DU of IAB node 300-1 via a transport channel. The MAC layer of the IAB-DU includes a scheduler. The scheduler determines the transport format (transport block size, modulation and coding scheme (MCS)) and the assigned resource blocks for uplink and downlink.

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

[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 donor gNB 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 donor gNB 200. When there is an RRC connection with the donor gNB 200, the IAB-MT is in the RRC connected state. When there is no RRC connection with the donor gNB 200, the IAB-MT is in the RRC idle state.

[0043] 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 IAB-MT of the IAB node 300-2 and the AMF 11.

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

[0045] As shown in Fig. 7, each of the IAB-MT of the IAB node 300-2, the IAB-DU of the IAB node 300-1, the IAB-MT of the IAB node 300-1, and the DU of the donor gNB 200 has a BAP (Backhaul Adaptation Protocol) layer as a 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 through the BAP layer, enabling routing in multiple hops.

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

[0047] 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.

[0048] (First embodiment) When a failure occurs in the BH link between the IAB node 300 and a donor gNB (hereinafter sometimes referred to as the "IAB donor") 200-1, the IAB node 300 becomes unable to transmit UL packets to the IAB donor 200-1.

[0049] In this case, if the IAB node 300 transfers a UL packet to the IAB donor 200-2, which is different from the IAB donor 200-1, the IAB donor 200-2 cannot decipher the packet even if it receives it. This is because the UL packet is originally a packet transferred from the UE 100 to the IAB donor 200-1, and is encrypted between the UE 100 and the IAB donor 200-1 by the PDCP connection.

[0050] In the first embodiment, the IAB node 300 transmits the UL packet to the IAB donor 200-2 by re-routing. Then, the IAB donor 200-2 forwards the UL packet to the IAB donor 200-1 through the data forwarding path set between the IAB donor 200-2 and the IAB donor 200-1.

[0051] As a result, the UL packet forwarded to the IAB donor 200-2 is sent to the original IAB donor 200-1, and the IAB donor 200-1 decrypts the UL packet and makes it possible to send it to the UPF 12.

[0052] In addition, re-routing between the IAB donors 200-1 and 200-2 in this manner may be referred to as Inter-donor-DU re-routing (or Inter-donor re-routing). Hereinafter, Inter-donor-DU re-routing may be referred to as "re-routing".

[0053] 9 is a diagram showing an example of the operation of the first embodiment. The cellular communication system 1 shown in FIG.

[0054] In step S100, an RRC connected state is established between the IAB node 300 and the IAB donor 200-1. The IAB node 300 is subordinate to the IAB donor 200-1.

[0055] In step S101, the IAB donor 200-1 transmits a dual donor request to the IAB donor 200-2. For example, the IAB donor 200-1 transmits the dual donor request to the IAB donor 200-2 using the Xn interface.

[0056] A dual donor request will contain at least one of the following three pieces of information: 1) BAP address of IAB node that allows re-routing 2) Termination information for data forwarding between donors (e.g. TNL (Transport Network Layer) addresses) 3) Current routing configuration (including at least the IAB node that will be performing re-routing)

[0057] In the example of Fig. 9, the above 1) is the BAP address of the IAB-MT of the IAB node 300. In the example of Fig. 9, the above 2) includes the TNL address of the IAB donor 200-1, etc. In the example of Fig. 9, the above 3) includes information regarding the routing between the IAB node 300 and the IAB donor 200-1.

[0058] The IAB donor 200-2 that receives the dual donor request may generate a routing configuration for re-routing based on at least any one of the information 1) to 3) included in the dual donor request. In the example of Fig. 9, such a routing configuration may include a setting for a path between the IAB node 300 and the IAB donor 200-2.

[0059] In step S102, the IAB donor 200-2 transmits an acknowledgment (Dual donor request ack) to the IAB donor 200-1 for the dual donor request.

[0060] The positive response contains at least one of the following three pieces of information: 4) BAP address of IAB donor's (own) DU 5) Termination information for data forwarding between donors (TNL addresses, etc.) 6) Routing settings for IAB donor generated re-routing

[0061] In the example of Figure 9, the above 4) is the BAP address of the DU of IAB donor 200-2. In the example of Figure 9, the above 5) includes the TNL address of IAB donor 200-2. In the example of Figure 9, the above 6) includes settings related to the path between IAB node 300 and IAB donor 200-2 generated by IAB donor 200-2.

[0062] By receiving the positive response to the dual donor request, the IAB donor 200-1 can obtain the TNL address of the IAB donor 200-2 as the termination information of the IAB donor 200-2. Also, the IAB donor 200-2 can obtain the TNL address of the IAB donor 200-1 as the termination information of the IAB donor 200-1 included in the dual donor request of step S101. Note that, in steps S101 and S102, an example in which the IAB donor 200-1 transmits the dual donor request and the IAB donor 200-2 transmits the positive response has been shown, but this is not limiting. In step S101, the IAB donor 200-2 may transmit the dual donor request, and in step S102, the IAB donor 200-1 may transmit the positive response. Also, in step S102, the IAB donor 200-1 may transmit a negative response. A negative response is sent if the dual donor request is not accepted.

[0063] Therefore, in step S103, the IAB donors 200-1 and 200-2 can form a connection (tunnel) for data forwarding between the IAB donors 200-1 and 200-2. The IAB donors 200-1 and 200-2 set a path for data forwarding based on the TNL addresses of the IAB donors 200-1 and 200-2.

[0064] In step S104, the IAB donor 200-1 transmits an RRC reconfiguration message to the IAB node 300 to perform RRC reconfiguration.

[0065] The RRC reconfiguration message may include at least the following three pieces of information: 7) Updated routing information (including paths for re-routing) 8) Indicator that allows inter-donor re-routing 9) BAP address of another donor's DU

[0066] However, the above 9) is optional, and indicates that such a BAP address may be notified.

[0067] In the example of Fig. 9, the above 7) includes information on the path between the IAB donor 200-1 and the IAB donor 200-2, information on the routing setting including the IAB donor 200-2, etc. Regarding the above 8), re-routing may be permitted for each BH RLC channel. Regarding the above 9), it is also possible to use it in the third embodiment described later.

[0068] In step S105, the IAB donor 200-1 reconfigures the F1 interface by transmitting an F1 configuration update message to the IAB node 300. The F1 reconfiguration update message may include at least the above 7) to 9).

[0069] Note that either one of the RRC reconfiguration in step S104 and the F1 configuration update in step S105 may be performed, or both may be performed as shown in Fig. 9. When either one of the processes is performed, the information from 7) to 9) above is included in the message on which the process is performed. When both of the processes are performed, the information from 7) to 9) above may be included in both messages, or part of the information from 7) to 9) above may be included in one message and the remaining information may be included in the other message.

[0070] In step S106, the IAB node 300 transmits an RRC reconfiguration complete message to the IAB donor 200-1.

[0071] The normal route for a UL packet (or data) that is not re-routed is from step S107 to step S109.

[0072] That is, in step S107, the IAB node 300 receives a packet transmitted from a subordinate IAB node or the UE 100. In step S108, the IAB node 300 transmits the received packet to the IAB donor 200-1. In step S108, the IAB donor 200-1 decrypts the received packet, and in step S109, transmits the decrypted packet to the UPF 12 (or the network).

[0073] On the other hand, when re-routing is performed, the process is as follows: That is, in step S110, the IAB node 300 receives a packet transmitted from a subordinate IAB node or the UE 100.

[0074] In step S111, the IAB node 300 performs re-routing. For example, the IAB node 300 performs re-routing in response to receiving a Type 1 Indication (notification of detection of backhaul link failure), a Type 2 Indication (notification of recovery from backhaul link failure), or a Type 1 / 2 Indication from a higher-level node (an upper-level IAB node or the IAB donor 200). In addition, the IAB node 300 may determine to perform re-routing to the IAB donor 200-2 based on information related to the routing configuration including the IAB donor 200-2 in step S104 and / or step S105.

[0075] In step S112, the IAB node 300 transmits the packet to the IAB donor 200-2 by re-routing. For example, the IAB node 300 may add marking to the packet to be re-routed and transmit the packet to the IAB donor 200-2.

[0076] In steps S113 and S114, the IAB donor 200-2 data-forwards the received (re-routed) packet to the IAB donor 200-1 in the state of a PDCP PDU. The IAB donor 200-2 may data-forward the packet on which the marking has been performed.

[0077] In step S115, the IAB donor 200-1 decrypts the received packet (PDCP PDU).

[0078] In step S116, the IAB donor 200-1 forwards the decrypted packet to the UPF 12.

[0079] By the above-described re-routing, the UL packet is forwarded from the IAB node 300 to the IAB donor 200-1 via the IAB donor 200-2. For example, even if a failure occurs between the IAB node 300 and the IAB donor 200-1, the UL packet can be forwarded from the IAB node 300 to the IAB donor 200-1.

[0080] Second embodiment In the first embodiment, an example of inter-donor re-routing in the UL direction of packets has been described. In the second embodiment, an example of inter-donor re-routing in the DL (Downlink) direction will be described.

[0081] FIG. 10 is a diagram illustrating an operation example of the second embodiment.

[0082] 10, in the second embodiment, the processes from S100 to S106 are performed in the same manner as in the first embodiment. However, the IAB node 300 in the second embodiment is in an RRC connected state with the IAB donor 200-2 and is an IAB node under the IAB donor 200-2.

[0083] The normal route for DL ​​packets (data) that is not re-routed is from step S120 to step S123.

[0084] That is, in step S120, the IAB donor 200-2 receives a packet transmitted from the UPF 12. In step S121, the IAB donor 200-2 encrypts the received packet. In step S122, the IAB donor 200-2 transmits the encrypted packet to the IAB node 300. In step S123, the IAB node 300 transmits the received packet to a lower IAB node or the UE 100.

[0085] On the other hand, when re-routing is performed because the DL packet cannot be directly transmitted from the IAB donor 200-2 to the IAB node 300 for some reason, the procedure is as follows: That is, in step S125, the IAB donor 200-2 receives a packet addressed to the destination (a lower node of the IAB node 300 or the UE 100).

[0086] In step S126, the IAB donor 200-2 encrypts the packet.

[0087] In step S127, the IAB donor 200-2 transmits the encrypted packet to the IAB donor 200-1 using the path for data forwarding.

[0088] In step S128, the IAB donor 200-1 transmits the packet received from the IAB donor 200-2 to the IAB node 300. Then, the IAB node 300 transmits the packet to the lower node or the UE 100.

[0089] In addition, the IAB donor 200-1 and the IAB donor 200-2 may share information on the BAP address of the IAB node 300.

[0090] In this way, also in the second embodiment, if a DL packet transmitted to the IAB donor 200-2 cannot be transmitted directly from the IAB donor 200-2 to the IAB node 300, it can be transmitted to the destination via the IAB donor 200-1.

[0091] Third embodiment In the first embodiment, an example has been described in which a new routing setting is made to a route from the IAB node 300 to the IAB donor 200-1 via the IAB donor 200-2. In the third embodiment, a path that can be re-routed is searched for without a new routing setting (or without changing the routing setting).

[0092] FIG. 11 is a diagram showing an example of the configuration of a cellular communication system 1 in the third embodiment.

[0093] 11, an IAB node 300-1 exists under an IAB donor 200-1, and an IAB node 300-2 exists as a lower node thereof. Also, an IAB node 300-3 exists under the IAB donor 200-2.

[0094] 12 is a diagram showing an example of operation in the third embodiment. The example of operation in FIG. 12 will be described with reference to the configuration example in FIG.

[0095] As shown in FIG. 12, in step S140, the cellular communication system 1 starts the process.

[0096] In step S141, the IAB donor 200 notifies the IAB node 300 of the BAP address of another IAB donor that can be re-routed. In the example of FIG. 11, the IAB donor 200-2 notifies the IAB node 300-3 of the BAP address of the DU of the IAB donor 200-1 that can be re-routed. Step 141 is the same as the process in which the IAB donor 200-1 transmits the BAP address of the DU of the IAB donor 200-2 to the IAB node 300 in step S104 and / or step S105 of the first embodiment, for example. Note that instead of step 141 shown in FIG. 12, the IAB node 300 may be able to grasp the BAP address of the DU of another IAB donor by another method.

[0097] In step S142, the IAB node 300 determines to perform re-routing. In the example of Fig. 11, the IAB node 300-1 may determine to perform re-routing by receiving a Type 1 Indication, a Type 2 Indication, or a Type 1 / 2 Indication.

[0098] The Type 1 Indication is an example of a failure occurrence notification indicating that a BH RLF (Radio Link Failure) has been detected. The Type 2 Indication is an example of a failure occurrence notification indicating that recovery from a BH RLF is being attempted. The Type 1 / 2 Indication is an example of a failure occurrence notification in which no distinction is made between the Type 1 Indication and the Type 2 Indication.

[0099] Returning to FIG. 12, in step S143, the IAB node 300 inquires of the surrounding IAB nodes whether or not they have a path to the IAB donor 200 connected to the IAB node 300 itself. In the example of FIG. 11, the IAB node 300-1 inquires of the surrounding IAB nodes 300-2 and 300-3 whether or not they have a path to the IAB donor 200-1 connected to the IAB node 300-1. The inquiry message may be, for example, a BAP Control PDU or a MAC CE. Alternatively, the inquiry message may use, for example, SIB1. When the IAB node 300-1 connects to multiple IAB donors 200, the inquiry message may include multiple BAP addresses in a list format.

[0100] Returning to FIG. 12, in step S144, if the surrounding IAB node has a path that can be re-routed, it transmits a response. In the example of FIG. 11, the IAB node 300-3 that has received the inquiry has a path to the IAB donor 200-1. That is, the IAB node 300-3 that has received the inquiry has been notified in advance of the BAP address of the DU of the IAB donor 200-1 that can be re-routed. The IAB node 300-3 confirms that this BAP address matches the BAP address of the DU of the IAB donor 200-1 included in the inquiry message. As a result, the IAB node 300-3 determines that re-routing is possible. The IAB node 300-3 transmits a response message to the IAB node 300-1. The response message may include a donor identifier that has a path. The donor identifier may be a destination BAP address (in the example of FIG. 11, the BAP address of the DU of the IAB donor 200-1), or if there are multiple destination BAP addresses, they may be expressed in a list format. Note that the response message may be transmitted by the BAP Control PDU, MAC CE, or SIB1, just like the inquiry message.

[0101] On the other hand, in the example of FIG. 11, the IAB node 300-2 also receives an inquiry from the IAB node 300-1. The IAB node 300-2 exists in the same topology as the IAB node 300-1. The IAB node 300-2 also has a path to the IAB donor 200-1. Therefore, the IAB node 300-2 also finds that the BAP address of the IAB donor 200-1 included in the inquiry message matches the BAP address of the IAB donor 200-2 to which the IAB node 300-2 has a path. Therefore, the IAB node 300-2 also determines that re-routing is possible, and transmits a response message to the IAB node 300-1.

[0102] Returning to FIG. 12, in step S145, the IAB node 300 re-routes the packet to the IAB node that transmitted the response message. In the example of FIG. 11, the IAB node 300-1 transmits the packet received from another node or the UE 100 to the IAB node 300-3. The IAB node 300-3 transmits the received packet to the IAB donor 200-1. As a result, for example, the packet is not forwarded directly from the IAB node 300-1 to the IAB donor 200-1, but is forwarded to the IAB donor 200-1 via the IAB node 300-3. Even if a failure occurs in the BH link between the IAB donor 200-1 and the IAB node 300-1, it is possible to forward the packet to the IAB donor 200-1, which is the destination, via the IAB node 300-3.

[0103] (Fourth embodiment) In 3GPP, Multi MT is being discussed. Multi MT is a technology in which, for example, the same IAB node 300 has multiple IAB-MTs, and each IAB-MT connects to a different IAB donor 200. Multi MT makes it possible to secure routes from one IAB node to multiple IAB donors 200. This makes it possible to secure or increase route redundancy.

[0104] In the case of downstream, in order to ensure route redundancy, there may be a path from the first IAB donor 200-1 to the IAB node 300 via the second IAB donor 200-2, and a path from the first IAB donor 200-1 directly to the IAB node 300. When multiple IAB-MTs operate independently in one IAB node, it is not clear whether multiple IAB-MTs exist in the same IAB node 300 or in separate IAB nodes 300 in the BAP address space. When multiple IAB-MTs exist in the same IAB node 300, it becomes possible to route packets in the same manner as in the second embodiment.

[0105] FIG. 13 is a diagram showing an example of the configuration of a cellular communication system 1 in the fourth embodiment.

[0106] 13, the IAB node 300 has two IAB-MTs, 350-1 and 350-2. The IAB node 300 also has an IAB-DU 360. The IAB-MT 350-1 is connected to the IAB donor 200-1. On the other hand, the IAB-MT 350-2 is connected to the IAB donor 200-2.

[0107] 14 is a diagram showing an example of operation of the fourth embodiment. The example of operation shown in FIG. 14 will be described using the configuration example in FIG.

[0108] As shown in FIG. 14, in step S150, the cellular communication system 1 starts the process.

[0109] In step S151, a BAP address is set to each of the IAB nodes 300 having multiple IAB-MTs by the connected IAB donor 200. In the example of Fig. 13, a BAP address #1 is set to the IAB-MT 350-1 by the DU of the IAB donor 200-1. A BAP address #2 is set to the IAB-MT 350-2 by the DU of the IAB donor 200-2. In the following description, the terms "setting" and "assignment" may be used interchangeably.

[0110] Returning to Fig. 14, in step S152, the IAB node 300 transmits BAP addresses with different setting sources to each donor 200. In the example of Fig. 13, the IAB-MT 350-1 transmits the BAP address #2 set in the IAB-MT 350-2 to the IAB donor 200-1. Also, the IAB-MT 350-2 transmits the BAP address #1 set in the IAB-MT 350-1 to the IAB donor 200-2. Note that the IAB node 300 may transmit BAP addresses with different setting sources when the BAP address is initially set or when the BAP address is changed.

[0111] Returning to Fig. 14, in step S153, each donor 200 associates the received BAP address with the BAP address it has set. In the example of Fig. 13, the IAB donor 200-1 associates the BAP address #2 received from the IAB-MT 350-1 with the BAP address #1 it has set in the IAB node 300. The IAB donor 200-2 associates the BAP address #1 received from the IAB-MT 350-2 with the BAP address #2 it has set in the IAB node 300. The IAB donors 200-1 and 200-2 may perform such association by determining that the received BAP address and the BAP address they have set are the same IAB node.

[0112] 14, in step S154, each donor 200 performs re-routing as necessary, and in step S155, the cellular communication system 1 ends the series of processes.

[0113] Fifth embodiment In the fourth embodiment, the problem in the case of downstream has been described. With regard to multi-MT, there is also a problem in the case of upstream. That is, packets need to be routed between the BAP addresses set in each IAB-MT in the IAB node 300. This can occur even in the case of downstream.

[0114] In the fifth embodiment, the multi-MT IAB node 300 requests the IAB donor 200 to set the same BAP address. By setting the same BAP address for multiple IAB-MTs for one IAB node 300, the multiple IAB donors 200 can recognize it as one IAB node. It is also possible to secure routes from multiple IAB donors 200 to the same IAB node 300, making it possible to secure route redundancy. In addition, there may be cases where packet routing between BAP addresses is not required.

[0115] Fig. 15 is a diagram showing an example of operation in the fifth embodiment. The example of operation shown in Fig. 15 will be explained using the configuration example in Fig. 13 as appropriate.

[0116] As shown in FIG. 15, in step S160, the cellular communication system 1 starts the process.

[0117] In step S161, the IAB node 300 having multiple IAB-MTs is set with a BAP address #1 from the IAB donor #1. In the example of Fig. 13, the IAB-MT 350-1 of the IAB node 300 is set with a BAP address #1 from the IAB donor 200-1.

[0118] Returning to Fig. 15, in step S162, the IAB node 300 transmits the set BAP address #1 to the IAB donor #2 when a connection to the IAB donor #2 is established. In the example of Fig. 13, the IAB-MT 350-2 of the IAB node 300 transmits the BAP address #1 to the IAB donor 200-2 when a connection to the IAB donor 200-2 is established. The set BAP address is transmitted, for example, by using at least one of the following messages. 10) RRC Setup Request, RRC Resume Request 11) RRC Setup Complete, RRC Resume Complete 12) F1 Setup Request, F1 Configuration Update

[0119] Each message may include an identifier indicating that the IAB node 300 has multiple IAB-MTs (or is a multi-MT).

[0120] 15, in step S163, the IAB donor #2 may set the same BAP address #1 as the assigned BAP address #1 received in step S162 to the IAB node 300. Since the BAP address #1 is set to the IAB node 300 in step S161, step S163 may not be necessary.

[0121] In step S164, the IAB node 300 may transmit a notification to the IAB donor #1 indicating that the same BAP address #1 is set for multiple IAB-MTs. Step S164 may be performed in the IAB donor #1 to prevent the BAP address #1 from being changed carelessly. Step S164 may not be required.

[0122] In step S165, each of the IAB donors #1 and #2 performs routing setting using the BAP address #1.

[0123] Then, in step S166, the cellular communication system 1 ends the series of processes.

[0124] (Other embodiments) A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in the computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0125] In addition, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC).

[0126] 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 and the like are possible without departing from the scope of the invention. In addition, it is also possible to combine all or part of each embodiment as long as there is no contradiction.

[0127] This application claims priority to U.S. Provisional Application No. 63 / 104034 (October 22, 2020), the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0128] 1: Mobile communication systems 10:5GC 11: AMF 12: UPF 100(100-1~100-3):UE 110: Wireless communication unit 111: Receiving unit 112: Transmitter 120: Control section 200(200-1,200-2):IAB donor 210: Wireless Communication Department 211: Receiving unit 212: Transmission unit 220: Network Communication Department 221: Receiving unit 222: Transmission unit 300 (300-1, 300-2, 300-3): IAB node 310: Wireless Communication Department 311: Receiving unit 312: Transmission unit 320: Control section

Claims

1. A donor node having a relay node under it, a transmitter configured to transmit a request message to the other donor node for migrating traffic of the relay node between the donor node and the other donor node; a receiving unit that receives a response message to the request message from the other donor node, The request message includes information indicating a Transport Network Layer (TNL) address for the traffic transition. Donor node.

2. A communication method executed in a donor node having a relay node thereunder, comprising: sending a request message to the other donor node to migrate traffic of the relay node between the donor node and the other donor node; receiving a response message to the request message from the other donor node; The request message includes information indicating a Transport Network Layer (TNL) address for the traffic transition. Communication methods.

3. A processor that controls a donor node having a relay node thereunder, sending a request message to the other donor node to migrate traffic of the relay node between the donor node and the other donor node; receiving a response message to the request message from the other donor node; The request message includes information indicating a Transport Network Layer (TNL) address for the traffic transition. Processor.

4. A communication system having a donor node having a relay node thereunder and another donor node, the donor node sending a request message to the other donor node to migrate traffic of the relay node between the donor node and the other donor node; The other donor node transmits a response message to the donor node in response to the request message; The request message includes information indicating a Transport Network Layer (TNL) address for the traffic transition. Communication systems.

5. A program for controlling a donor node having a relay node under its control, sending a request message to the other donor node to migrate traffic of the relay node between the donor node and the other donor node; receiving a response message from the other donor node in response to the request message; The request message includes information indicating a Transport Network Layer (TNL) address for the traffic transition. program.

Images