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

Abstract

A communication control method according to a first aspect of the present invention is used in a cellular communication system. The communication control method includes transmitting a first packet from a first relay node belonging to a first donor base station to a second donor base station different from the first donor base station. The communication control method further comprises the steps that the second donor base station forwards the first packet to the first donor base station through the data forwarding path; and the first donor base station transmitting the first packet to the network.

Description

[0001] This application is a divisional application of the Chinese invention patent application "Communication control method, first donor base station and second donor base station" with an application date of October 21, 2021 and application number 202180086336.2. Technical Field

[0002] The present invention relates to a communication control method used in a cellular communication system. Background Art

[0003] In the 3rd Generation Partnership Project (3GPP), which is a cellular communication system standardization project, the introduction of a new relay node called an integrated access and backhaul (IAB) node is being considered (for example, see "3GPP TS 38.300 V16.2.0 (2020-07)"). One or more relay nodes participate in the communication between the base station and the user equipment and perform relaying of the communication. Summary of the invention

[0004] In a first aspect, a communication control method is used in a cellular communication system. The communication control method includes: sending a first packet to a second donor base station different from the first donor base station by a first relay node subordinate to the first donor base station. The communication control method includes: forwarding the first packet to the first donor base station by the second donor base station using a path for data forwarding; and sending the packet to a network by the first donor base station.

[0005] In a second aspect, a communication control method is used in a cellular communication system. The communication control method includes: a first relay node subordinate to a first donor base station queries a second relay node whether the second relay node includes a path to the first donor base station, the second relay node being subordinate to a second donor base station different from the first donor base station. The communication control method includes: when the second relay node includes the path to the first donor base station, the second relay node sends a response to the query to the first relay node.

[0006] In a third aspect, a communication control method is used in a cellular communication system. The communication control method includes: a first user equipment function of a relay node sends a second BAP address configured by a second donor base station for a second user equipment function of the relay node to a first donor base station, and the first user equipment function is configured with a first BAP address by the first donor base station. The communication control method includes: a second user equipment function sends the first BAP address to the second donor base station.

[0007] In a fourth aspect, a communication control method is used in a cellular communication system. The communication control method includes configuring a relay node using a first BAP address for a first user equipment function from a first donor base station, the relay node including the first user equipment function. The communication control method includes sending, by the relay node, a second BAP address to the second donor base station when establishing a connection to the second donor base station. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a diagram showing a configuration example of a cellular communication system according to an embodiment.

[0009] Figure 2 is a diagram showing the relationship between IAB nodes, parent nodes, and child nodes.

[0010] Figure 3 is a diagram showing a configuration example of a gNB (base station) according to an embodiment.

[0011] Figure 4 is a diagram showing a configuration example of an IAB node (relay node) according to the embodiment.

[0012] Figure 5 is a diagram showing a configuration example of a UE (User Equipment) according to an embodiment.

[0013] Figure 6 is a diagram showing an example of a protocol stack related to an RRC connection and a NAS connection of an IAB-MT.

[0014] Figure 7 is a diagram showing an example of a protocol stack related to the F1-U protocol.

[0015] Figure 8 is a diagram showing an example of a protocol stack related to the F1-C protocol.

[0016] Fig. 9 is a diagram showing a configuration example of a cellular communication system according to the first embodiment.

[0017] Fig.10 is a diagram showing an operation example according to the second embodiment.

[0018] Fig.11 is a diagram showing a configuration example of a cellular communication system according to the third embodiment.

[0019] Fig.12 is a diagram showing an operation example according to the third embodiment.

[0020] Fig.13 is a diagram showing a configuration example of a cellular communication system according to a fourth embodiment.

[0021] Fig.14 is a diagram showing an operation example according to the fourth embodiment.

[0022] Fig.15 is a diagram showing an operation example according to the fifth embodiment. DETAILED DESCRIPTION

[0023] A cellular communication system according to an embodiment is described with reference to the accompanying drawings. In the description of the drawings, the same or similar parts are represented by the same or similar reference numerals.

[0024] Configuration of cellular communication systems

[0025] A configuration example of a cellular communication system according to an embodiment is described. In the embodiment, the cellular communication system 1 is a 3GPP 5G system. Specifically, the radio access scheme in the cellular communication system 1 is a new radio (NR) as a 5G radio access scheme. Note that Long Term Evolution (LTE) may be at least partially applied to the cellular communication system 1. Future cellular communication systems such as 6G may be applied to the cellular communication system 1.

[0026] Figure 1 is a diagram showing a configuration example of a cellular communication system 1 according to the embodiment.

[0027] like Figure 1 As shown, the cellular communication system 1 includes a 5G core network (5GC) 10, a user equipment (UE) 100, base station devices (hereinafter also referred to as base stations) 200-1 and 200-2, and IAB nodes 300-1 and 300-2. The base station 200 can be referred to as a gNB.

[0028] The following mainly describes an example in which the base station 200 is an NR base station, but the base station 200 may also be an LTE base station (i.e., eNB).

[0029] Note that, hereinafter, base stations 200-1 and 200-2 may be referred to as gNB 200 (or base station 200), and IAB nodes 300-1 and 300-2 may be referred to as IAB nodes 300.

[0030] 5GC 10 includes an access and mobility management function (AMF) 11 and a user plane function (UPF) 12. AMF 11 is a device that performs various types of mobility control, etc. for UE 100. AMF 11 communicates with UE 100 by using non-access stratum (NAS) signaling, thereby managing information of an area in which UE 100 exists. UPF 12 is a device that performs transmission control of user data, etc.

[0031] Each gNB 200 is a fixed wireless communication node and manages one or more cells. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" may be used to indicate a function or resource used to perform wireless communication with the UE 100. One cell belongs to one carrier frequency. In the following, a cell and a base station may be used without distinction.

[0032] Each gNB 200 is interconnected with the 5GC 10 via an interface called the NG interface. Figure 1 gNB 200-1 and gNB 200-2 connected to 5GC 10 are shown.

[0033] Each gNB 200 may be divided into a central unit (CU) and a distributed unit (DU). The CU and the DU are interconnected 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 as a control plane protocol and an F1-U protocol as a user plane protocol.

[0034] The cellular communication system 1 supports IAB, which uses NR for backhaul to implement wireless relay for NR access. The donor gNB 200-1 is a donor base station that is a terminal node of the NR backhaul on the network side and includes additional functions for supporting IAB. The backhaul can implement multi-hop via multiple hops (i.e., multiple IAB nodes 300).

[0035] Figure 1 An example is shown in which the IAB node 300-1 is wirelessly connected to the donor gNB 200-1, the IAB node 300-2 is wirelessly connected to the IAB node 300-1, and the F1 protocol is sent via two backhaul hops.

[0036] UE 100 is a mobile wireless communication device that performs wireless communication with a cell. UE 100 may be any type of device as long as UE 100 is a device that performs wireless communication with gNB 200 or IAB node 300. For example, UE 100 includes a mobile phone terminal, a tablet terminal, a laptop PC, a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle, and an aircraft or a device provided on an aircraft. UE 100 is wirelessly connected to IAB node 300 or gNB 200 via an access link. Figure 1 An example is shown in which the UE 100 is wirelessly connected to the IAB node 300-2. The UE 100 communicates indirectly with the donor gNB 200-1 via the IAB node 300-2 and the IAB node 300-1.

[0037] Figure 2 is a diagram showing the relationship between the IAB node 300, parent nodes, and child nodes.

[0038] like Figure 2 As shown, each IAB node 300 includes an IAB-DU corresponding to a base station function and an IAB-mobile terminal (MT) corresponding to a user equipment function.

[0039] The neighboring node (i.e., upper node) of the IAB-MT of the NR Uu radio interface is called a "parent node". The parent node is the parent IAB node or the DU of the donor gNB 200. The radio link between the IAB-MT and each parent node is called a backhaul link (BH link). Figure 2 An example is shown in which the parent nodes of the IAB node 300 are the IAB nodes 300P1 and 300P2. Note that the direction toward the parent node is referred to as upstream. The upper node of the UE 100 may correspond to the parent node.

[0040] The neighboring node (i.e., the lower node) of the IAB-DU of the NR access interface is called a "child node". The IAB-DU manages the cell in the same and / or similar manner as the gNB200. The IAB-DU terminates the NR Uu radio interface connected to the UE 100 and the lower IAB node. The IAB-DU supports the F1 protocol for the CU of the donor gNB 200-1. Figure 2 An example is shown in which the child nodes of the IAB node 300 are the IAB nodes 300C1 to 300C3 but the child nodes of the IAB node 300 may include the UE 100. Note that a direction toward the child nodes is referred to as downstream.

[0041] Base station configuration

[0042] A configuration of gNB 200 as a base station according to an embodiment is described. Figure 3 2 is a diagram showing a configuration example of gNB 200. Figure 3 As shown, gNB 200 includes a wireless communicator 210, a network communicator 220 and a controller 230.

[0043] The wireless communicator 210 performs wireless communication with the UE 100 and the IAB node 300. The wireless communicator 210 includes a receiver 211 and a transmitter 212. The receiver 211 performs various types of reception under the control of the controller 230. The receiver 211 includes an antenna, converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal) to output the baseband signal to the controller 230. The transmitter 212 performs various types of transmission under the control of the controller 230. The transmitter 212 includes an antenna and converts (up-converts) a baseband signal (transmission signal) output by the controller 230 into a radio signal, and then transmits the radio signal from the antenna.

[0044] The network communicator 220 performs wired communication (or wireless communication) with the 5GC 10 and another neighboring gNB 200. The network communicator 220 includes a receiver 221 and a transmitter 222. The receiver 221 performs various types of reception under the control of the controller 230. The receiver 221 receives a signal from an external source and outputs the received signal to the controller 230. The transmitter 222 performs various types of transmission under the control of the controller 230. The transmitter 222 sends a transmission signal output by the controller 230 to an external destination.

[0045] The controller 230 performs various types of control in the eNB 200. The controller 230 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs to be executed by the processor and information to be used by the processor for processing. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, encoding and decoding of baseband signals, etc. The CPU executes the program stored in the memory to perform various types of processing. The processor performs the processing of the following layers. In each embodiment described below, the controller 230 may perform all processing in the gNB 200.

[0046] Relay node configuration

[0047] The configuration of the IAB node 300 as a relay node (or a relay node device, which is also referred to as a “relay node” hereinafter) according to the embodiment is described. Figure 4 is a diagram showing a configuration example of the IAB node 300. Figure 4 As shown, IAB node 300 includes a wireless communicator 310 and a controller 320. IAB node 300 may include a plurality of wireless communicators 310.

[0048] The wireless communicator 310 performs wireless communication (BH link) with the gNB 200 and wireless communication (access link) with the UE 100. The wireless communicator 310 for BH link communication and the wireless communicator 310 for access link communication may be provided separately.

[0049] The wireless communicator 310 includes a receiver 311 and a transmitter 312. The receiver 311 performs various types of reception under the control of the controller 320. The receiver 311 includes an antenna, converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal) to output the baseband signal to the controller 320. The transmitter 312 performs various types of transmission under the control of the controller 320. The transmitter 312 includes an antenna and converts (up-converts) a baseband signal (transmitted signal) output by the controller 320 into a radio signal, and then transmits the radio signal from the antenna.

[0050] The controller 320 performs various types of control in the IAB node 300. The controller 320 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs to be executed by the processor and information to be used by the processor for processing. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, encoding and decoding of baseband signals, etc. The CPU executes the program stored in the memory to perform various types of processing. The processor performs the processing of the following layers. In each embodiment described below, the controller 320 can perform all processing in the IAB node 300.

[0051] User equipment configuration

[0052] Next, a configuration of UE 100 as user equipment according to the embodiment is described. Figure 5 is a diagram showing the configuration of UE 100. Figure 5 As shown, UE 100 includes a wireless communicator 110 and a controller 120.

[0053] The wireless communicator 110 performs wireless communication in the access link, that is, wireless communication with the gNB 200 and wireless communication with the IAB node 300. The wireless communicator 110 may also perform wireless communication in the side link, that is, wireless communication with another UE 100. The wireless communicator 110 includes a receiver 111 and a transmitter 112. The receiver 111 performs various types of reception under the control of the controller 120. The receiver 111 includes an antenna and converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and then transmits the baseband signal to the controller 120. The transmitter 112 performs various types of transmission under the control of the controller 120. The transmitter 112 includes an antenna and converts (up-converts) a baseband signal (transmitted signal) output by the controller 120 into a radio signal, and then transmits the radio signal from the antenna.

[0054] The controller 120 performs various types of control in the UE 100. The controller 120 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs to be executed by the processor and information to be used by the processor for processing. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, encoding and decoding of baseband signals, etc. The CPU executes the program stored in the memory, thereby performing various types of processing. The processor performs the processing of the following layers. In each embodiment described below, the controller 120 can perform all processing in the UE 100.

[0055] Protocol stack configuration

[0056] Next, the configuration of the protocol stack according to the embodiment is described. Figure 6is a diagram showing an example of a protocol stack related to an RRC connection and a NAS connection of an IAB-MT.

[0057] like Figure 6 As shown, the IAB-MT of the IAB node 300-2 includes 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.

[0058] The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and 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.

[0059] The MAC layer performs priority control of data, retransmission processing by hybrid ARQ (HARQ: Hybrid Automatic Repeat Request), random access procedures, etc. Data and control information are transmitted between the MAC layer of the IAB-MT of the IAB node 300-2 and the MAC layer of the IAB-DU of the 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 assignment of resource blocks in uplink and downlink.

[0060] The RLC layer transmits data to the RLC layer on the receiving side by using 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.

[0061] The PDCP layer performs header compression and decompression, as well as encryption and decryption. Data and control information are sent 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.

[0062] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, reestablishment, and release of radio bearers. RRC signaling for various configurations is sent 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 to the donor gNB 200, the IAB-MT is in the RRC connected state. When there is no RRC connection to the donor gNB 200, the IAB-MT is in the RRC idle state.

[0063] The NAS layer higher than 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.

[0064] Figure 7 is a diagram showing a protocol stack associated with the F1-U protocol. Figure 8 is a diagram showing a protocol stack related to the F1-C protocol. An example is shown in which the donor gNB 200 is divided into a CU and a DU.

[0065] like Figure 7 As shown, 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 includes a backhaul adaptation protocol (BAP) layer as a layer higher than the RLC layer. The BAP layer performs routing processing, and bearer mapping and demapping processing. In the backhaul, the IP layer is sent via the BAP layer to allow routing through multiple hops.

[0066] In each backhaul link, the protocol data unit (PDU) of the BAP layer is sent through the backhaul RLC channel (BH NR RLC channel). Configuring each BH link to include multiple backhaul RLC channels enables service prioritization and QoS control. The association between the BAPPDU and the backhaul RLC channel is performed by the BAP layer of each IAB node 300 and the BAP layer of the donor gNB 200.

[0067] like Figure 8 As shown, the protocol stack of the F1-C protocol includes the F1AP layer and the SCTP layer, instead of Figure 7 The GTP-U layer and UDP layer are shown.

[0068] First embodiment

[0069] When the BH link between the IAB node 300 and the donor gNB (hereinafter also referred to as "IAB donor") 200-1 fails, the IAB node 300 can no longer send UL packets to the IAB donor 200-1.

[0070] In this case, when the IAB node 300 forwards the UL packet to the IAB donor 200-2 which is different from the IAB donor 200-1, the IAB donor 200-2 cannot decrypt the packet even when receiving the packet. This is because the UL packet is originally forwarded from the UE 100 to the IAB donor 200-1 and is encrypted through the PDCP connection between the UE 100 and the IAB donor 200-1.

[0071] In the first embodiment, the IAB node 300 transmits the UL packet to the IAB donor 200-2 by rerouting. The IAB donor 200-2 then forwards the UL packet to the IAB donor 200-1 through the data forwarding path configured between the IAB donor 200-2 and the IAB donor 200-1.

[0072] Therefore, the UL packet forwarded to the IAB donor 200 - 2 is sent to the original IAB donor 200 - 1 , enabling the IAB donor 200 - 1 to decrypt the UL packet and send the UL packet to the UPF 12 .

[0073] Note that rerouting via the IAB donors 200-1 and 200-2 in this manner may be referred to as donor inter-DU rerouting (or inter-donor rerouting). Donor inter-DU rerouting may be referred to as "rerouting" hereinafter.

[0074] Fig. 9 : is a diagram showing an operation example of the first embodiment. Fig. 9 The illustrated cellular communication system 1 is an example including an IAB node 300 , two IAB donors 200 - 1 and 200 - 2 , and a UPF 12 .

[0075] In step S100, the IAB node 300 and the IAB donor 200-1 are in an RRC connection state. The IAB node 300 is subordinate to the IAB donor 200-1.

[0076] In step S101, the IAB donor 200-1 sends a dual donor request to the IAB donor 200-2. For example, the IAB donor 200-1 sends the dual donor request to the IAB donor 200-2 using an Xn interface.

[0077] The dual donor request includes at least one of the following three pieces of information.

[0078] 1) BAP address of the IAB node that allows rerouting

[0079] 2) Termination information for data forwarding between donors (Transport Network Layer (TNL) address, etc.)

[0080] 3) Current routing configuration (including at least the IAB node that is performing the rerouting)

[0081] The above 1) is Fig. 9 The BAP address of the IAB-MT of the IAB node 300 in the example. The above 2) includes Fig. 9 The TNL address of the IAB donor 200-1 in the example. The above 3) includes the Fig. 9 The information of the route between the IAB node 300 and the IAB donor 200-1 in the example.

[0082] The IAB donor 200-2 having received the dual donor request may generate a routing configuration for rerouting based on at least one of the information 1) to 3) included in the dual donor request. Fig. 9 In the example of , such routing configuration may include configuration for a path between the IAB node 300 and the IAB donor 200 - 2 .

[0083] In step S102, the IAB donor 200-2 sends an acknowledgement (Dual Donor Request Acknowledgement) to the IAB donor 200-1 in response to the Dual Donor Request.

[0084] The positive response includes at least one of the following three pieces of information.

[0085] 4) BAP address of the DU of the IAB donor (itself)

[0086] 5) Termination information for data forwarding between donors (TNL address, etc.)

[0087] 6) Routing configuration for rerouting generated by IAB donor

[0088] The above 4) is Fig. 9 In the example of IAB donor 200-2, the BAP address of the DU is shown. The above 5) includes Fig. 9 The TNL address of the IAB donor 200-2 in the example. The above 6) includes Fig. 9 2 is a configuration of a path between the IAB node 300 and the IAB donor 200 - 2 generated by the IAB donor 200 - 2 .

[0089] The IAB donor 200-1 may receive the positive response in response to the dual donor request to obtain the TNL address of the IAB donor 200-2 as the termination information of the IAB donor 200-2. The IAB donor 200-2 may also 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 steps S101 and S102 describe an example in which the IAB donor 200-1 sends the dual donor request and the IAB donor 200-2 sends the positive response, but the present invention is not limited thereto. In step S101, the IAB donor 200-2 may send the dual donor request, and in step S102, the IAB donor 200-1 may send the positive response. In step S102, the IAB donor 200-1 may send a negative response. When the dual donor request is not accepted, a negative response is sent.

[0090] In step S103, the IAB donors 200-1 and 200-2 can thus form a connection (tunnel) for data forwarding between the IAB donors 200-1 and 200-2. The IAB donors 200-1 and 200-2 configure a path for data forwarding based on the TNL addresses of the IAB donors s200-1 and 200-2.

[0091] In step S104, the IAB donor 200-1 sends an RRC reconfiguration message to the IAB node 300 to perform RRC reconfiguration.

[0092] The RRC reconfiguration message may include at least three of the following information.

[0093] 7) Updated routing information (including paths used for rerouting)

[0094] 8) Indicator indicating that inter-donor rerouting is allowed

[0095] 9) BAP address of another donor's DU

[0096] Note that the above 9) is optional and is information indicating that such a BAP address can be sent.

[0097] The above 7) includes information about the path between the IAB donor 200-1 and the IAB donor 200-2, and information about the path including Fig. 9 The above 8) may indicate that rerouting is allowed for each BH RLC channel. The above 9) may also be used for the third embodiment described later.

[0098] In step S105, the IAB donor 200-1 sends an F1 configuration update message to the IAB node 300 to reconfigure the F1 interface. The F1 reconfiguration update message may include at least the above 7) to 9).

[0099] Note that only one of the processes of RRC reconfiguration in step S104 and F1 configuration update in step S105 may be performed, or both may be performed as shown in FIG. Fig. 9 If only one of the processes is performed, the above information 7) to 9) is included in the message of the process to be performed. If two processes are performed, the above information 7) to 9) may be included in two messages, or part of the above information 7) to 9) may be included in one message, and the rest of the information may be included in the other message.

[0100] In step S106, the IAB node 300 sends an RRC reconfiguration complete message to the IAB donor 200-1.

[0101] Normal routing of UL packets (or data) without rerouting corresponds to step S107 to step S109.

[0102] Specifically, in step S107, the IAB node 300 receives a packet transmitted from the lower 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).

[0103] On the other hand, when rerouting is performed, the following operations are performed: Specifically, in step S110 , the IAB node 300 receives a packet transmitted from a lower IAB node or the UE 100 .

[0104] In step S111, the IAB node 300 performs rerouting. For example, the IAB node 300 performs rerouting in response to receiving a type 1 indication (indication of backhaul link failure detection), a type 2 indication (indication during backhaul link failure recovery), or a type 1 indication / type 2 indication from an upper node (IAB donor 200 or an IAB node located at an upper layer). In step S104 and / or step S105, the IAB node 300 may determine to perform rerouting to the IAB donor 200-2 based on information about a routing configuration including the IAB donor 200-2.

[0105] In step S112, the IAB node 300 transmits the packet by rerouting to the IAB donor 200-2. For example, the IAB node 300 may add a tag to the packet to be rerouted and transmit the packet to the IAB donor 200-2.

[0106] In steps S113 and S114, the IAB donor 200-2 performs data forwarding of the received (rerouted) packet to the IAB donor 200-1 in the PDCP PDU state. The IAB donor 200-2 may perform data forwarding of the marked packet.

[0107] In step S115, the IAB donor 200-1 decrypts the received packet (PDCP PDU).

[0108] In step S116 , the IAB donor 200 - 1 forwards the decrypted packet to the UPF 12 .

[0109] By rerouting as described above, UL packets are forwarded from IAB node 300 to IAB donor 200-1 via IAB donor 200-2. For example, even when a failure or the like occurs between IAB node 300 and IAB donor 200-1, UL packets can be forwarded from IAB node 300 to IAB donor 200-1.

[0110] Second embodiment

[0111] In the first embodiment, an example of inter-donor rerouting in the UL direction of packets is described. In the second embodiment, an example of inter-donor rerouting in the downlink (DL) direction is described.

[0112] Fig.10 is a diagram showing an operation example according to the second embodiment.

[0113] like Fig.10 As shown, in the second embodiment, the processes in S100 to S106 are performed as in the first embodiment. However, the IAB node 300 in the second embodiment is in the RRC connection state with the IAB donor 200-2 and is subordinate to the IAB donor 200-2.

[0114] Normal routing of DL packets (or data) without rerouting corresponds to step S120 to step S123.

[0115] Specifically, in step S120, the IAB donor 200-2 receives the packet sent from the UPF 12. In step S121, the IAB donor 200-2 encrypts the received packet. In step S122, the IAB donor 200-2 sends the encrypted packet to the IAB node 300. In step S123, the IAB node 300 sends the received packet to the lower IAB node or the UE 100.

[0116] On the other hand, when rerouting is performed because the DL packet cannot be directly sent from the IAB donor 200-2 to the IAB node 300 for some reason, the process is as follows: Specifically, in step S125, the IAB donor 200-2 receives a packet addressed to the destination (the lower node of the IAB node 300 or the UE 100).

[0117] In step S126, the IAB donor 200-2 encrypts the packet.

[0118] In step S127, the IAB donor 200-2 transmits the encrypted packet to the IAB donor 200-1 using the path for data forwarding.

[0119] In step S128, the IAB donor 200-1 transmits the packet received from the IAB donor 200-2 to the IAB node 300. The IAB node 300 then transmits the packet to the down node or UE 100.

[0120] Note that the IAB donors 200 - 1 and 200 - 2 may share information on the BAP address of the IAB node 300 .

[0121] In this manner, also in the second embodiment, when a DL packet transmitted to the IAB donor 200-2 cannot be directly transmitted from the IAB donor 200-2 to the IAB node 300, the DL packet can be transmitted to the destination via the IAB donor 200-1.

[0122] Third embodiment

[0123] In the first embodiment, an example is described in which routing configuration is newly performed for routing from the IAB node 300 to the IAB donor 200-1 via the IAB donor 200-2. In the third embodiment, a reroutable path is searched without performing new routing configuration (or without changing the routing configuration).

[0124] Fig.11 is a diagram showing a configuration example of a cellular communication system 1 according to the third embodiment.

[0125] like Fig.11 As shown, there is an IAB node 300-1 subordinate to the IAB donor 200-1 and there is an IAB node 300-2 as a node lower than the IAB node 300-1. There is also an IAB node 300-3 subordinate to the IAB donor 200-2.

[0126] Fig.12 2 is a diagram showing an operation example according to the third embodiment. Fig.11 The configuration example in Fig.12 An example of operation in .

[0127] like Fig.12 As shown, in step S140, the cellular communication system 1 starts processing.

[0128] In step S141, the IAB donor 200 sends the BAP address of another IAB donor that can be re-routed to the IAB node 300. Fig.11In the example of , IAB donor 200-2 sends the BAP address of the DU of IAB donor 200-1 which can be rerouted to IAB node 300-3. The process in step S141 is the same as the process in step S104 and / or step S105 of the first embodiment, for example, in which IAB donor 200-1 sends the BAP address of the DU of IAB donor 200-2 to IAB node 300. Note that instead of Fig.12 As shown in step S141 , another method may be used to allow the IAB node 300 to identify the BAP address of the DU of another IAB donor.

[0129] In step S142, the IAB node 300 determines to perform rerouting. Fig.11 In the example of FIG. 5 , the IAB node 300 - 1 may receive a type 1 indication, a type 2 indication, or a type 1 indication / type 2 indication to determine to perform rerouting.

[0130] Note that the Type 1 indication is an example of a failure occurrence notification indicating that a BH RLF (Radio Link Failure) is 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 indication / Type 2 indication is an example of a failure occurrence notification when the Type 1 indication and the Type 2 indication are not distinguished from each other.

[0131] return Fig.12 In step S143, the IAB node 300 queries the surrounding IAB nodes whether the surrounding IAB nodes have a path to the IAB donor 200, which is connected to the IAB node 300 itself. Fig.11 In the example of , the IAB node 300-1 queries the surrounding IAB nodes 300-2 and 300-3 whether the IAB nodes 300-2 and 300-3 have a path to the IAB donor 200-1, which is connected to the IAB node 300-1. The query message may be, for example, a BAP control PDU or a MAC CE. Alternatively, the query message may use, for example, SIB 1. When the IAB node 300-1 is connected to multiple IAB donors 200, the query message may include multiple BAP addresses in a list form.

[0132] return Fig.12 In step S144, if the surrounding IAB nodes have a reroutable path, they send a response. Fig.11In the example of , the queried IAB node 300-3 has a path to the IAB donor 200-1. In other words, the BAP address of the DU of the IAB donor 200-1 that can be re-routed is sent to the queried IAB node 300-3 in advance. The IAB node 300-3 confirms that the BAP address matches the BAP address of the DU of the IAB donor 200-1 included in the query message. Therefore, the IAB node 300-3 determines that rerouting is possible. The IAB node 300-3 sends a response message to the IAB node 300-1. The response message may include an identifier of the donor having the path. The donor identifier may be the destination BAP address ( Fig.11 1). If multiple destination BAP addresses are available, these addresses may be represented in the form of a list. Note that the response message may be sent via a BAP control PDU, MAC CE, or SIB 1 in the same and / or similar manner as the query message.

[0133] On the other hand, Fig.11 In the example of , IAB node 300-2 also receives the query from IAB node 300-1. IAB node 300-2 exists in the same topology as IAB node 300-1. IAB node 300-2 also has a path to IAB donor 200-1. Therefore, also in IAB node 300-2, the BAP address of IAB donor 200-1 included in the query message matches the BAP address of IAB donor 200-2 to which IAB node 300-2 has a path. Therefore, IAB node 300-2 also determines that rerouting is possible, and sends a response message to IAB node 300-1.

[0134] return Fig.12 In step S145, the IAB node 300 reroutes the packet to the IAB node to which the IAB node 300 has sent the response message. Fig.11 In the example of , the IAB node 300-1 transmits a packet received from another node or UE 100 to the IAB node 300-3. The IAB node 300-3 transmits the received packet to the IAB donor 200-1. Therefore, for example, instead of forwarding the packet directly from the IAB node 300-1 to the IAB donor 200-1, the packet is forwarded to the IAB donor 200-1 via the IAB node 300-3. Even when a failure occurs in the BH link between the IAB donor 200-1 and the IAB node 300-1, the packet can be forwarded to the IAB donor 200-1 as the destination via the IAB node 300-3.

[0135] Fourth embodiment

[0136] In 3GPP, multi-MT is being discussed. Multi-MT is a technology in which, for example, the same IAB node 300 includes multiple IAB-MTs, and each IAB-MT is connected to a different IAB donor 200. Through multi-MT, routing from one IAB node to multiple IAB donors 200 can be ensured. Therefore, routing redundancy can be ensured or increased.

[0137] In the case of the downstream, in order to ensure routing 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 a plurality of IAB-MTs operate independently in one IAB node, in the BAP address space, it is not known whether the plurality of IAB-MTs exist in the same IAB node 300 or in different IAB nodes 300. If the plurality of IAB-MTs exist in the same IAB node 300, the packet may be routed by operations that are the same as and / or similar to those of the second embodiment.

[0138] Fig.13 is a diagram showing a configuration example of a cellular communication system 1 according to the fourth embodiment.

[0139] exist Fig.13 In the example of FIG. 3 , the IAB node 300 includes two IAB-MTs 350-1 and 350-2. The IAB node 300 includes an IAB-DU 360. The IABMT 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.

[0140] Fig.14 2 is a diagram showing an operation example according to the fourth embodiment. Fig.13 The configuration example in Fig.14 Operation example shown.

[0141] like Fig.14 As shown, in step S150, the cellular communication system 1 starts processing.

[0142] In step S151, the IAB node 300 including a plurality of IAB-MTs is configured with the BAP addresses from the respective connected IAB donors 200. Fig.13 In the example of , IAB-MT 350-1 is configured with BAP address #1 of the DU from IAB donor 200-1. IAB-MT 350-2 is configured with BAP address #2 of the DU from IAB donor 200-2. Note that in the following description, "configure" and "assign" may be used indiscriminately.

[0143] return Fig.14 In step S152, the IAB node 300 sends a BAP address with different configuration sources to each donor 200. Fig.13 In the example of FIG. 1 , IAB-MT 350-1 sends BAP address #2 configured for IAB-MT 350-2 to IAB donor 200-1. IAB-MT 350-2 sends BAP address #1 configured for IAB-MT 350-1 to IAB donor 200-2. Note that IAB node 300 may send BAP addresses with different configuration sources at the time of initial configuration of the BAP address or when the configuration of the BAP address changes.

[0144] return Fig.14 In step S153, each donor 200 associates the received BAP address with the BAP address configured by the donor 200 itself. Fig.13 In the example of FIG. 1 , the IAB donor 200-1 associates the BAP address #2 received from the IAB-MT 350-1 with the BAP address #1 configured by the IAB donor 200-1 itself for 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 configured by the IAB donor 200-2 itself for the IAB node 300. Each of the IAB donors 200-1 and 200-2 may determine that the received BAP address and the BAP address configured by the IAB donor 200 itself are from the same IAB node, and thus associate the BAP addresses.

[0145] return Fig.14 In step S154, each IAB donor 200 performs rerouting as needed. In step S155, the cellular communication system 1 then ends a series of processes.

[0146] Fifth embodiment

[0147] In the fourth embodiment, the problem occurring in the downstream case is described. For multiple MTs, there is also the problem occurring in the upstream case. That is, it is necessary to perform packet routing between the BAP addresses configured for each IAB-MT in the IAB node 300. This can occur even in the downstream case.

[0148] In the fifth embodiment, the multi-MT IAB node 300 requests the IAB donor 200 to configure the same BAP address. For one IAB node 300, the same BAP address is configured for multiple IAB-MTs so that multiple IAB donors 200 can identify the IAB node 300 as one IAB node. Multiple IAB donors 200 can also ensure that each is routed to the same IAB node 300 to ensure routing redundancy. It may not be necessary to perform packet routing between BAP addresses.

[0149] Fig.15 FIG. 1 is a diagram showing an operation example according to the fifth embodiment. Fig.13 The configuration example in Fig.15 Operation example shown.

[0150] like Fig.15 As shown, in step S160, the cellular communication system 1 starts processing.

[0151] In step S161, the IAB node 300 including a plurality of IAB-MTs is configured with the BAP address #1 from the IAB donor #1. Fig.13 In the example of FIG. 3 , the IAB-MT 350 - 1 of the IAB node 300 is configured with the BAP address # 1 from the IAB donor 200 - 1 .

[0152] return Fig.15 In step S162, the IAB node 300 sends the configured BAP address #1 to the IAB donor #2 when establishing a connection to the IAB donor #2. Fig.13 In the example of FIG. 1 , the IAB-MT 350-2 of the IAB node 300 transmits the BAP address #1 to the IAB donor 200-2 when establishing a connection to the IAB donor 200-2. The configured BAP address is transmitted by using, for example, at least one of the following messages.

[0153] 10)RRC establishment request, RRC recovery request,

[0154] 11) RRC establishment is completed, RRC recovery is completed,

[0155] 12) F1 establishment request, F1 configuration update

[0156] Note that each message may include an identifier indicating that the IAB node 300 includes a plurality of IAB-MTs (or Multi-MTs).

[0157] return Fig.15In step S163, IAB donor #2 may configure the same BAP address #1 as the assigned BAP address #1 received in step S162 for IAB node 300. Note that in step S161, IAB node 300 is configured with BAP address #1, so step S163 may be omitted.

[0158] In step S164, the IAB node 300 may send a notification to the IAB donor #1 indicating that the same BAP address #1 is configured for multiple IAB-MTs. Step S164 may be performed to prevent or reduce the occurrence of accidental changes in the BAP address #1 in the IAB donor #1. Step S164 may also be omitted.

[0159] In step S165, each of the IAB donors #1 and #2 performs routing configuration using the BAP address #1.

[0160] In step S166, the cellular communication system 1 then ends a series of processes.

[0161] Other embodiments

[0162] A program that causes a computer to execute each process performed by the UE 100 or the gNB 200 may be provided. The program may be recorded in a computer-readable medium. The program can be installed on a computer using a computer-readable medium. 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 specifically limited and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0163] Circuits for performing processing to be performed by UE 100 or gNB 200 may be integrated, and at least a portion of UE 100 or gNB 200 may be configured as a semiconductor integrated circuit (chip set or SoC).

[0164] Although the embodiments have been described in detail with reference to the drawings, the specific configuration is not limited to the above configuration, and various design modifications and the like may be made without departing from the scope of the present invention. All or part of the embodiments may be combined together as long as no contradiction is introduced.

[0165] This application claims priority to U.S. Provisional Application No. 63 / 104,034 (filed on October 22, 2020), the entire contents of which are incorporated herein by reference.

[0166] Reference numerals

[0167] 1: Mobile communication system

[0168] 10:5GC

[0169] 11: AMF

[0170] 12: UPF

[0171] 100 (100-1 to 100-3): UE

[0172] 110: Wireless Communicator

[0173] 111: Receiver

[0174] 112: Transmitter

[0175] 120: Controller

[0176] 200 (200-1, 200-2): IAB donor

[0177] 210: Wireless Communicator

[0178] 211: Receiver

[0179] 212: Transmitter

[0180] 220: Network Communicator

[0181] 221: Receiver

[0182] 222: Transmitter

[0183] 300 (300-1, 300-2, 300-3): IAB node

[0184] 310: Wireless communicator receiver transmitter controller.

Claims

1. A donor node, wherein there is a relay node subordinate to the donor node, and the donor node comprises: a transmitter configured to send a request message to another donor node, wherein the request message is used to transfer traffic of the relay node between the donor node and the another donor node; as well as a receiver configured to receive a response message to the request message from the other donor node, the response message including information about routing configuration, wherein: The transmitter is further configured to send the information about the routing configuration to the relay node, The receiver is further configured to receive, from the other donor node, a packet sent from the relay node to the other donor node, and The transmitter is further configured to send the packet to a network.

2. A communication method performed in a donor node, wherein there is a relay node subordinate to the donor node, the communication method comprising: Sending a request message to another donor node, wherein the request message is used to transfer traffic of the relay node between the donor node and the another donor node; receiving a response message to the request message from the other donor node, the response message including information about routing configuration; Sending the information about the routing configuration to the relay node; receiving, from the another donor node, a packet transmitted from the relay node to the another donor node; and The packet is sent to the network.

3. A processor for controlling a donor node, wherein there is a relay node subordinate to the donor node, and the processor performs the following processing: Sending a request message to another donor node, wherein the request message is used to transfer traffic of the relay node between the donor node and the another donor node; receiving a response message to the request message from the other donor node, the response message including information about routing configuration; Sending the information about the routing configuration to the relay node; receiving, from the another donor node, a packet transmitted from the relay node to the another donor node; and The packet is sent to the network.

4. A communication system having a donor node and another donor node, wherein there is a relay node subordinate to the donor node, The donor node sends a request message to another donor node, where the request message is used to transfer traffic of the relay node between the donor node and the other donor node; The other donor node sends a response message to the request message to the donor node, wherein the response message includes information about routing configuration; The donor node sends the information about the routing configuration to the relay node; The relay node sends a packet to the another donor node; The another donor node forwards the packet to the donor node; and The donor node sends the packet to a network.

5. A program product for controlling a donor node, wherein there is a relay node subordinate to the donor node, and the program product causes the donor node to perform the following processing: Sending a request message to another donor node, wherein the request message is used to transfer traffic of the relay node between the donor node and the another donor node; receiving a response message to the request message from the other donor node, the response message including information about routing configuration; Sending the information about the routing configuration to the relay node; receiving, from the another donor node, a packet transmitted from the relay node to the another donor node; and The packet is sent to the network.

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