Signal transmission / reception method, device, and communication system

Abstract

An embodiment of the present invention provides a signal transmission / reception method, an apparatus and a communication system, the signal transmission / reception apparatus being applied to a first access backhaul integrated node donor aggregation unit (IAB-donor-CU), the apparatus including a first transceiver, the first transceiver being configured to send a traffic offload request to a second IAB-donor-CU, and receive a response agreeing to the traffic offload or a response rejecting the traffic offload sent by the second IAB-donor-CU.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present invention relates to the field of communications technology. [Background technology]

[0002] Integrated access and backhaul (IAB) realizes the function of radio relay in next generation radio access network (NG-RAN). Integrated access and backhaul node (IAB-node) supports access and backhaul via new radio (NR). The network side end of NR backhaul is called IAB-donor, which represents a network device (e.g. gNB) that supports IAB function.

[0003] An IAB node can be connected to one IAB-donor via single or multi-hop connections. These multi-hop connections form a topological structure of a Directed Acyclic Graph (DAG) with the IAB-donor as the root node. The IAB-donor performs centralized resource management, topology management, and routing management of the IAB network topology.

[0004] The IAB-node supports the function of gNB-DU (distributed unit). The IAB-node DU is also called IAB-DU, which is the termination point of the radio access (NR access) interface between the terminal equipment (UE) and the next hop IAB-node, and the termination point of the F1 protocol to the gNB-CU (IAB-node: aggregation unit) at the IAB-donor. The IAB-DU can provide services to normal UE and IAB child nodes. The IAB-DU realizes the function of the network side device, connects to the downstream child IAB-node, provides the NR air interface to the UE and the downstream child IAB-node, and establishes the F1 connection between the IAB donor-CU.

[0005] In addition to the gNB-DU functionality, the IAB-node supports a part of the UE functionality called IAB-MT (mobile termination). The IAB-MT includes, for example, physical layer, layer 2, RRC, and NAS functionality for connecting to a gNB-DU of another IAB-node or IAB-donor, connecting to a gNB-CU at the IAB-donor, and connecting to the core network. The IAB-MT can support, for example, UE physical layer, access stratum (AS), radio resource control (RRC), and non-access stratum (NAS) layer functionality, and can connect to an IAB parent node.

[0006] The IAB-donor is a network-side end node that provides network access for the IAB-MT or UE via a backhaul or access link. The IAB-donor is further divided into an IAB-donor-CU (central unit) and an IAB-donor-DU. The IAB-DU and the IAB-donor-CU are connected via an F1 interface. In a network-only deployment scenario, the gNB and the IAB-donor-CU are connected via an Xn interface.

[0007] To support multi-hop routing forwarding of packets, the IAB introduces the Backhaul Adaptation Protocol (BAP) sublayer, which sits above the Radio Link Control (RLC) sublayer and below the IP layer and supports functions such as packet target node and route selection, packet routing forwarding, bearer mapping, flow control feedback, and backhaul link failure notification.

[0008] FIG. 1 is a schematic diagram of an example of an IAB topology structure. As shown in FIG. 1, in the IAB topology structure 10, an IAB-node 100 includes an IAB-MT functional unit 101 and an IAB-DU functional unit 102, and adjacent nodes at the interface of the IAB-DU functional unit 102 are called child nodes, and include, for example, child nodes 201, 202, and 203 shown in FIG. 1. The IAB-DU functional unit 102 and the child nodes 201, 202, and 203 can communicate with each other via an air interface (Uu). The adjacent nodes at the interface of the IAB-MT functional unit 101 are called parent nodes, and include, for example, parent nodes 301 and 302 shown in FIG. 1. The IAB-MT functional unit 101 and the parent nodes 301 and 302 can communicate with each other via an air interface (Uu).

[0009] 1, the direction from the IAB-node 100 to the child nodes 201, 202, 203 is referred to as the downstream direction, and the direction from the IAB-node 100 to the parent nodes 301, 302 is referred to as the upstream direction. An IAB-donor (not shown) performs centralized resource, topology, and routing management for the IAB topology structure 10.

[0010] The above description of the background art is merely for the purpose of more clearly and completely explaining the configurations of the present invention and for the understanding of those skilled in the art, and should not be construed as meaning that these configurations are well known to those skilled in the art just because they are described in the background art of the present invention. Summary of the Invention [Problem to be solved by the invention]

[0011] Topology redundancy refers to establishing a redundant path, i.e., a second path, for an IAB node in an IAB topology network to offload partial services in one topology network to another topology network, i.e., data transmission through the redundant path. The main purpose of topology redundancy is to achieve service load balancing, reduce service interruptions, and improve network robustness.

[0012] The conventional intra-CU topology redundancy procedure can establish and release redundant paths in the IAB topology in the same IAB-donor-CU, and this procedure can achieve a certain degree of path diversity and load balancing. When the load is saturated in the topology network in the same IAB-donor-CU, it will affect the performance of the service. The inter-CU topology redundancy can further improve the path diversity and better meet the needs of load balancing.

[0013] However, as discovered by the inventors of the present invention, there is no corresponding solution for how to establish or release topologically redundant paths between donors.

[0014] An embodiment of the present invention provides a signal transmission / reception method, device, and communication system, in which a redundant path can be established between the network topology of the first IAB-donor-CU and the network topology of the second IAB-donor-CU by a first IAB-donor-CU sending a traffic offload request to a second IAB-donor-CU, and the second IAB-donor-CU sending a response to the first IAB-donor-CU agreeing to the traffic offload or rejecting the traffic offload, thereby further improving path diversity and better meeting the needs of load balancing and reduced service interruptions. [Means for solving the problem]

[0015] In one aspect of an embodiment of the present invention, a signal transceiver device applied to a first access backhaul integrated node donor aggregation unit (IAB-donor-CU) is provided, the device including a first transceiver unit configured to send a traffic offload request to a second IAB-donor-CU and receive a response agreeing to the traffic offload or a response rejecting the traffic offload sent by the second IAB-donor-CU.

[0016] Another aspect of an embodiment of the present invention provides a signal transceiver apparatus applied to a second access backhaul integrated node donor aggregation unit (IAB-donor-CU), the apparatus including a second transceiver unit configured to receive a traffic offload request sent by a first IAB-donor-CU and to send a response agreeing to the traffic offload or a response rejecting the traffic offload to the first IAB-donor-CU.

[0017] In another aspect of an embodiment of the present invention, there is provided a signal transceiver apparatus, applied to an IAB node, the IAB node being connected to a first parent node, the IAB node being already connected or to be connected to a second parent node, the first parent node being a node in a topology of a first IAB-donor-CU, the second parent node being a node in a topology of a second IAB-donor-CU, the apparatus including a third transceiver, the third transceiver being configured to receive a first RRC reconfiguration message sent by the first IAB-donor-CU and to send an RRC reconfiguration complete message to the first IAB-donor-CU, The present invention provides an apparatus, wherein a first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to the first IAB-donor-CU, the first RRC reconfiguration message includes at least one TNL address assigned to a DU of the IAB node, the TNL address being anchored to a second IAB-donor-DU in a topology of the second IAB-donor-CU, and the RRCReconfigurationComplete message is used to indicate that the IAB node has received the first RRC reconfiguration message and has completed reconfiguration.

[0018] In another aspect of an embodiment of the present invention, there is provided a signal transceiver apparatus, applied to a descendant node of an IAB node, the IAB node being connected to a first parent node, the IAB node being already connected or to be connected to a second parent node, the first parent node being a node in a topology of a first IAB-donor-CU, and the second parent node being a node in a topology of a second IAB-donor-CU, the apparatus including a fourth transceiver, the fourth transceiver configured to receive a first RRC reconfiguration message sent by the first IAB-donor-CU and to send an RRC reconfiguration complete message to the first IAB-donor-CU. the first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to the first IAB-donor-CU, the first RRC reconfiguration message includes at least one TNL address assigned to a DU of the descendant node, the TNL address being anchored to a second IAB-donor-DU in a topology of the second IAB-donor-CU, and the RRCReconfigurationComplete message is used to indicate that the descendant node has received the first RRC reconfiguration message and has completed the reconfiguration.

[0019] Another aspect of the present invention provides a signal transmission / reception method corresponding to the signal transmission / reception device according to any one of the above aspects.

[0020] The advantageous effects of the embodiment of the present invention are as follows: A first IAB-donor-CU sends a traffic offload request to a second IAB-donor-CU, and the second IAB-donor-CU sends a response to the first IAB-donor-CU agreeing to the traffic offload or rejecting the traffic offload, thereby establishing a redundant path between the network topology of the first IAB-donor-CU and the network topology of the second IAB-donor-CU.

[0021] As shown in the following description and drawings, certain embodiments of the present invention are disclosed in detail to show the manner in which the principles of the present invention can be employed. However, the scope of the embodiments of the present invention is not limited to these. The embodiments of the present invention include modifications, alterations and equivalents within the spirit and scope of the appended claims.

[0022] Features described and / or illustrated in one embodiment may be used in the same or similar manner in one or more other embodiments and may be combined with or substituted for features in other embodiments.

[0023] It should be noted that in this text, the term "including / having" means the presence of a feature, element, step or component, and does not exclude the presence or addition of one or more other features, elements, steps or components. [Brief description of the drawings]

[0024] Elements and features depicted in one drawing and one embodiment of the present invention may be combined with elements and features shown in one or more drawings or embodiments, and in the drawings, like reference numerals may designate corresponding elements in multiple drawings and may designate corresponding elements used in more than one embodiment. [Figure 1] FIG. 2 is a schematic diagram of an example of an IAB topology structure. [Diagram 2] FIG. 13 is a diagram illustrating an example of a topology transmission path in an inter-CU topology redundancy scenario. [Diagram 3] 2 is a schematic diagram illustrating an example of a signal transmission / reception method according to the first embodiment. [Figure 4] 11 is a schematic diagram illustrating an example of a signal transmission / reception method according to a second embodiment. FIG. [Diagram 5] FIG. 11 is a schematic diagram of an example of a procedure for establishing a second route of an IAB node in the first embodiment; [Figure 6]FIG. 13 is a schematic diagram of an example of a method for establishing redundant paths between donors for descendant nodes of an IAB node in Example 2. [Figure 7] FIG. 1 is a schematic diagram illustrating adding an SN to an IAB node to change it into a dual-connection node and establish a redundant path. [Figure 8] FIG. 1 is a schematic diagram of an example of a successful traffic offload procedure. [Figure 9] FIG. 1 is a schematic diagram of an example of a failed traffic offload procedure. [Figure 10] FIG. 13 is a schematic diagram of an example of redundant path release by the initiator of traffic offload. [Figure 11] FIG. 13 is a schematic diagram of an example of a redundant path release by a traffic offload recipient; [Figure 12] FIG. 11 is a schematic diagram of an example of a signal transmission and reception method according to a third embodiment. [Figure 13] FIG. 11 is a schematic diagram of an example of a signal transmission and reception method according to a third embodiment. [Figure 14] 1 is a schematic diagram of an example of a signal transmitting / receiving device according to an embodiment of the present invention. [Figure 15] 13 is a schematic diagram of an example of a signal transmitting / receiving device according to a sixth embodiment. FIG. [Figure 16] 13 is a schematic diagram of an example of a signal transmitting / receiving device according to a seventh embodiment. FIG. [Figure 17] 13 is a schematic diagram of an example of a signal transmitting / receiving device according to an eighth embodiment. FIG. [Figure 18] 1 is a schematic diagram of a configuration of a network device according to an embodiment of the present invention. [Figure 19] FIG. 2 is a schematic diagram of a terminal device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The above and other features of the present invention will become apparent from the following description. In the specification and drawings, specific embodiments of the present invention are disclosed in detail, and some of the embodiments in which the principles of the present invention can be employed are shown. However, the present invention is not limited to the described embodiments. The present invention includes all modifications, variations, and equivalents within the scope of the appended claims.

[0026] In embodiments of the present invention, the terms "first", "second", etc. are used in the title to distinguish different elements, but do not represent the spatial arrangement or temporal order of these elements, and these elements are not limited to these terms. The term "and / or" includes any and all combinations of one or more of the terms listed in the associated list. The terms "including", "comprising", "having", etc. refer to the presence of listed features, elements, elements or components, but do not exclude the presence or addition of one or more other features, elements, elements or components.

[0027] In the embodiments of the present invention, the singular forms "a", "the", etc., include the plural forms and should be understood broadly as "one kind" or "a class", and are not limited to "one". In addition, the term "said" should be understood to include both the singular and the plural forms, unless the context clearly indicates otherwise. In addition, the term "described in" should be understood to mean "described at least in part", and the term "based on" should be understood to mean "based at least in part on", unless the context clearly indicates otherwise.

[0028] In an embodiment of the present invention, the term "communication network" or "wireless communication network" may refer to a network conforming to any communication standard, such as, for example, new radio (NR), Long Term Evolution (LTE), Advanced Long Term Evolution (LTE-A, LTE-Advanced), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), etc.

[0029] Additionally, communications between devices in a communication system may occur according to any generation of communication protocols, including, but not limited to, 1G (generation), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G, 5G, and new radio (NR), and / or other currently known or future developed communication protocols.

[0030] In the embodiment of the present invention, the term "network device" refers to a device in a communication system, for example, allowing a terminal device to access the communication system and providing a service to the terminal device. The network device may include, but is not limited to, an access backhaul integration node (IAB-node), a base station (BS), an access point (AP), a transmission reception point (TRP), a broadcast transmitter, a mobility management entity (MME), a gateway, a server, a radio network controller (RNC), a base station controller (BSC), etc.

[0031] Among them, the base station may include, but is not limited to, a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), and a 5G base station (gNB), etc., as well as a Remote Radio Head (RRH), a Remote Radio Unit (RRU), a relay, or a low power node (e.g., femto, pico, etc.). Also, the term "base station" may include some or all of the functions thereof, and each base station may provide communication coverage for a particular geographic area. The term "cell" may refer to a base station and / or its coverage area depending on the context in which the term is used.

[0032] In the embodiment of the present invention, the term "User Equipment" (UE) or "Terminal Equipment" (TE) refers to an apparatus that accesses a communication network and receives a network service via, for example, a network device. The terminal apparatus may be fixed or mobile, and may be called a mobile station (MS), a terminal, a subscriber station (SS), an access terminal (AT), a station, etc.

[0033] Among them, the terminal device may include, but is not limited to, a mobile phone, a personal digital assistant (PDA), a wireless modulation / demodulation device, a wireless communication device, a handheld device, a machine-type communication device, a laptop computer, a cordless phone, a smartphone, a smart watch, a digital camera, and the like.

[0034] For example, in a scenario such as the Internet of Things (IoT), the user equipment may be a monitoring or measuring device or equipment, including, but not limited to, a Machine Type Communication (MTC) terminal, an in-vehicle communication terminal, a Device to Device (D2D) terminal, a Machine to Machine (M2M) terminal, etc.

[0035] Furthermore, the term "network side" or "network device side" refers to the side of a network, which may be a base station or may include one or more network devices as described above. The term "user side" or "terminal side" or "user terminal side" refers to the side of a user or terminal, which may be a UE or may include one or more terminal devices as described above.

[0036] In the embodiment of the present invention, the higher layer signaling may be, for example, Radio Resource Control (RRC) signaling, for example, referred to as an RRC message, including, for example, MIB, system information, dedicated RRC message, or referred to as an RRC information element (RRC IE). The higher layer signaling may be, for example, F1-C signaling, or referred to as an F1AP protocol. However, the present invention is not limited thereto.

[0037] In each embodiment of the present invention, multiple UEs are connected to an IAB-donor via multi-hop IAB nodes, and finally access a network, which is, for example, a 5G network.

[0038] 2 is a diagram showing an example of a topology transmission path in an inter-CU topology redundancy scenario. In FIG. 2, Donor-CU1 is also called IAB-donor-CU1, and Donor-CU2 is also called IAB-donor-CU2.

[0039] As shown in FIG. 2, Donor-CU1 is an F1 terminating donor of IAB node 3 and IAB node 4. IAB node 3 is a dual-connection node with two paths to Donor-CU1. IAB node 4 may also have two paths to Donor-CU1. Take IAB node 4 as an access IAB node as an example, some data from IAB node 4 to Donor-CU1 is transmitted through a topology network controlled by Donor-CU1 (called the first path, shown by a solid arrow), and some data is transmitted through a topology network controlled by Donor-CU2 (called the second path, shown by a dashed arrow), thereby achieving the purpose of data splitting and load balancing. Similarly, IAB node 3 and other descendant nodes (not shown) of IAB node 3 can also establish a second path as access IAB nodes.

[0040] In Figure 2, IAB node 1 is the first parent node of IAB node 3, IAB node 2 is the second parent node of IAB node 3, and IAB node 4 is a descendant node of IAB node 3. For simplicity, UEs below IAB node 4 are not depicted in Figure 2.

[0041] In each embodiment of the present invention, the first IAB-donor-CU may be Donor-CU1 in Fig. 2, the second IAB-donor-CU may be Donor-CU2 in Fig. 2, the IAB node may be IAB node 3 in Fig. 2, the descendant node of IAB node 3 may be IAB node 4 in Fig. 2, the first parent node of IAB node 3 may be IAB node 1 in Fig. 2, the second parent node of IAB node 3 may be IAB node 2 in Fig. 2, the first parent node of IAB node 3 (e.g., IAB node 1) is a node in the topology of the first IAB-donor-CU, and the second parent node of IAB node 3 (e.g., IAB node 2) is a node in the topology of the second IAB-donor-CU. The second IAB-donor-DU may be Donor-DU2 in Fig. 2.

[0042] In Fig. 2, when both the first path and the second path are established, the IAB node 3 is connected to a first parent node (e.g., IAB node 1) and the IAB node 3 is connected to a second parent node (e.g., IAB node 2). Furthermore, until the second path is established (i.e., before the signal transmission and reception method of the present invention is executed), the IAB node 3 and the second parent node (e.g., IAB node 2) may be already connected or may not be connected yet (i.e., to be connected).

[0043] In each embodiment of the present invention, the access IAB node includes an IAB node (e.g., IAB node 3 in FIG. 2) and / or a descendant node of an IAB node (e.g., IAB node 4 in FIG. 2), or an IAB node that is to be dual-connected (e.g., a node that is to be connected to a first IAB-donor-CU and a second IAB-donor-CU).

[0044] In the embodiments of the present invention, IAB-DU may represent a distributed unit of an IAB node, i.e., a DU of the IAB, and IAB-MT may represent a mobile terminal of an IAB node, i.e., a MT of the IAB.

[0045] In each embodiment of the present invention, a node in the topology of Donor-CU means that the DU part of the node is managed by Donor-CU, that is, the F1 interface of the node terminates on Donor-CU.

[0046] In each embodiment of the present invention, Donor-CU and IAB-donor-CU have the same meaning and may be replaced with each other.

[0047] <Embodiment 1> The first embodiment of the present invention provides a signal transmission and reception method. The method is applied to a first access backhaul integrated node donor aggregation unit (IAB-donor-CU). The first embodiment of the present invention describes the signal transmission and reception method from the first IAB-donor-CU side. Here, the first IAB-donor-CU may be, for example, Donor-CU1 in FIG. 2.

[0048] 3 is a schematic diagram of an example of a signal transmission and reception method according to embodiment 1. As shown in FIG. 3, the method includes the following steps:

[0049] Step 301: Send a traffic offload request to a second IAB-donor-CU.

[0050] Step 302: Receive a response agreeing to traffic offload or a response rejecting traffic offload sent by a second IAB-donor-CU.

[0051] In the present invention, steps 301 and 302 can support topology redundancy between the first IAB-donor-CU and the second IAB-donor-CU, so as to further improve the path diversity and better meet the needs of load balancing.

[0052] In at least one aspect, the traffic offload request sent in step 301 includes a request to establish a redundant path across a donor for the IAB node and / or a descendant node of the IAB node.

[0053] For example, the first IAB-donor-CU configures a backhaul radio link control (BH RLC) channel from the IAB node to a descendant node of the IAB node and configures a routing table of the BAP sublayer to support routing and BH RLC channel mapping of the second path, thereby establishing a redundant path for the descendant node. The first IAB-donor-CU may also configure a BAP route identifier mapping for the IAB node in response to agreeing to traffic offload. This allows the IAB node to perform a BAP route conversion between the topology of the first path controlled by the first IAB-donor-CU and the topology of the second path controlled by the second IAB-donor-CU to establish a redundant path for the descendant node. The first IAB-donor-CU may also migrate an F1-U tunnel from the first IAB-donor-CU to a DU of an IAB node and / or a descendant node of the IAB node from a first path to a second path via a UE CONTEXT MODIFICATION REQUEST message or a UE CONTEXT SETUP REQUEST message, thereby establishing a redundant path for the IAB node and / or the descendant node.

[0054] In at least one aspect, the response agreeing to traffic offload in step 302 may indicate at least partially accepting the traffic offload request, where at least partially accepting the traffic offload request means establishing redundant paths for F1-C tunnels associated with some TNLs or establishing redundant paths for some F1-U tunnels.

[0055] In at least one aspect, when the IAB node is connected to a first parent node and the IAB node is also connected to a second parent node, the traffic offload request may be included in a traffic offload request message, which may be, for example, a TRAFFIC OFFLOAD REQUEST message or may be a Redundant Path Establishment Request message. A response agreeing to the traffic offload may be included in a traffic offload request acknowledge message, which may be, for example, a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message. A response rejecting the traffic offload may be included in a traffic offload reject message, which may be, for example, a TRAFFIC OFFLOAD REQUEST REJECT message.

[0056] In one aspect, the traffic offload request message may include an identifier of the user equipment of the traffic offload initiating node at the Xn interface (UE XnAP ID) and / or one or more identities of F1-C, where the traffic offload initiating node refers to the first IAB-donor-CU, and the user equipment refers to the access IAB node (the IAB-donor is the user equipment of the IAB node), and the identities of F1-C are used to establish a redundant path for one or more F1-C of the access IAB node.

[0057] In another aspect, the traffic offload request message includes at least one of the UE XnAP ID of the traffic offload initiating node, the BAP address of the access IAB node, the TNL address, one or more F1-U tunnel identification information, IP header information of the F1-C and / or each F1-U tunnel, and Quality of Service (QoS) information of each F1-U tunnel.

[0058] In the above two aspects, when accepting the traffic offload request for at least a part of the F1-C and / or F1-U tunnel, the traffic offload request acknowledgement message may include at least one of the following: UE XnAP ID of the traffic offload initiating node, UE XnAP ID of the traffic offload accepting node, identification information of the F1-C and / or F1-U tunnel, newly allocated TNL address for the DU of the access IAB node, BH RLC channel identifier on the link between the dual-connected IAB node and the second parent node configured for the F1-C and / or F1-U tunnel, BAP address of the second parent node, BAP routing identifier in the topology controlled by the second IAB-donor-CU, and second BAP address of the IAB node. Here, the traffic offload accepting node means the second IAB-donor-CU. The UE XnAP ID of the traffic offload accepting node means the Xn interface ID in the node of the second IAB-donor-CU of the access IAB node. Depending on whether the traffic initiating node and the traffic accepting node correspond to an MN or an SN, the UE XnAP ID of the traffic initiating node and the UE XnAP ID of the traffic offload accepting node may be referred to as M-NG-RAN node UE XnAP ID (UE XnAP ID of master base station node) or S-NG-RAN node UE XnAP ID (UE XnAP ID of secondary base station node), respectively.

[0059] In the above two aspects, when rejecting the traffic offload request for all F1-C and F1-U tunnels, the second IAB-donor-CU sends a traffic offload request reject message, and the traffic offload request reject message includes the UE XnAP ID of the traffic offload initiation node.

[0060] In at least one aspect, when an IAB node is connected to a first parent node and also to a second parent node, when the first IAB-donor-CU is a master node (MN), the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or rejecting the traffic offload are included as information elements (IEs) in a message of a secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure of the XnAP.

[0061] In at least another embodiment, when the IAB node is connected to a first parent node and the IAB node is not connected to a second parent node, the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or rejecting the traffic offload may be included as information elements (IEs) in a message of the XnAP secondary base station node addition preparation (S-NG-RAN node addition preparation) procedure.

[0062] For example, the traffic offload request may be included in an S-NODE ADDITION REQUEST message sent by the first IAB-donor-CU to the second IAB-donor-CU. As another example, the response agreeing to the traffic offload may be included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU.

[0063] As shown in FIG. 3, the method further includes the following steps.

[0064] Step 303: In response to the response agreeing to the traffic offload, send a first RRC reconfiguration message to the IAB node and / or a descendant IAB node of the IAB node.

[0065] In step 303, the first RRC reconfiguration message may include at least one transport network layer (TNL) or transport layer address respectively assigned to a distributed unit (DU) of an IAB node (e.g., IAB node 3 in FIG. 2) and / or a descendant node of the IAB node (e.g., IAB node 4 in FIG. 2), which is anchored to a second IAB-donor-DU (e.g., Donor-DU2 in FIG. 2) in the topology of a second IAB-donor-CU.

[0066] In step 303, the BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a field for indicating a second BAP address configured for the IAB node, such as bap-Address-redundant or bap-Address-second to indicate that it is a second BAP address. Alternatively, the BAP address field in the BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a list, and each entry in the list is a BAP address and its related information. For example, the list may be a bap-AddressList, and each entry in the list is a BAP address and its related information, such as {bap-Address,'MCG' / 'SCG'} or {bap-Address,iab-donor-DU-BAP-Address}. This allows the second BAP address to be assigned for the IAB node 3. The second BAP address may be used for BAP routing configuration on a redundant path (i.e., a second path through Donor-DU2).

[0067] In at least one aspect, in step 303, if a new TNL address is assigned to the IAB node and / or its descendant nodes, the first IAB-donor-CU may add the new TNL address to the F1-C association between the DU of the IAB node and / or its descendant nodes and the first IAB-donor-CU.

[0068] As shown in FIG. 3, the signal transmission and reception method may further include the following steps.

[0069] Step 304: The first IAB-donor-CU sends or receives a redundant path release request.

[0070] Step 305: The first IAB-donor-CU receives or sends a redundant path release request acceptance message.

[0071] For example, the first IAB-donor-CU sends a redundant path release request to the second IAB-donor-CU, and the first IAB-donor-CU receives a redundant path release request acceptance message from the second IAB-donor-CU. As another example, the first IAB-donor-CU receives a redundant path release request sent by the second IAB-donor-CU, and the first IAB-donor-CU sends a redundant path release request acceptance message to the second IAB-donor-CU.

[0072] In at least one aspect, the redundant path release request includes a UE XnAP ID of a traffic offload initiating node, a UE XnAP ID of a traffic offload accepting node, a TNL address associated with the F1-C for which the redundant path needs to be released, or UP Transport Layer Information of the F1-U tunnel for which the redundant path needs to be released, where the redundant path is, for example, the second path shown in FIG.

[0073] In at least one aspect, when a master node (MN) in the first IAB-donor-CU and the second IAB-donor-CU transmits a redundant path release request, the contents of the redundant path release request and the contents of a redundant path release request acceptance message are included as IEs in a secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure.

[0074] In at least one aspect, when an IAB node secondary base station node release procedure is performed, all redundant paths associated with the IAB node in the SN topology are released.

[0075] According to embodiment 1 of the present invention, a redundant path can be established between the first IAB-donor-CU and the second IAB-donor-CU, so that the diversity of paths can be further improved and the needs of load balancing and reducing service interruption can be better met. Also, a topology redundant path between the first IAB-donor-CU and the second IAB-donor-CU can be released.

[0076] <Embodiment 2> The second embodiment of the present invention provides a signal transmission / reception method corresponding to the method of the first embodiment, at least for the same problems as the first embodiment. The signal transmission / reception method according to the second embodiment of the present invention is applied to a second access backhaul integrated node donor aggregation unit (IAB-donor-CU). The second embodiment of the present invention describes the signal transmission / reception method from the second IAB-donor-CU side. Here, the second IAB-donor-CU may be, for example, Donor-CU2 in FIG. 2.

[0077] 4 is a schematic diagram of an example of a signal transmission and reception method according to embodiment 2. As shown in FIG. 4, the method includes the following steps:

[0078] Step 401: Receive a traffic offload request sent by a first IAB-donor-CU.

[0079] Step 402: Send a response to the first IAB-donor-CU agreeing to the traffic offload or rejecting the traffic offload.

[0080] In the present invention, steps 401 and 402 can support topology redundancy between the first IAB-donor-CU and the second IAB-donor-CU, so as to further improve the path diversity and better meet the needs of load balancing.

[0081] In at least one aspect, the traffic offload request in step 401 includes a request to establish a redundant path for an IAB node (e.g., IAB node 3 in FIG. 2) and / or a descendant node of the IAB node (e.g., IAB node 4 in FIG. 2).

[0082] The response of agreeing to traffic offload in step 402 indicates at least partially accepting the traffic offload request, where at least partially accepting the traffic offload request means establishing redundant paths for F1-C or some F1-U tunnels associated with some TNLs.

[0083] If the IAB node is connected to a first parent node and if the IAB node is connected to a second parent node, the traffic offload request may be included in a traffic offload request message. A response agreeing to the traffic offload may be included in a traffic offload request acknowledge message, which may be, for example, a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message. A response rejecting the traffic offload may be included in a traffic offload reject message, which may be, for example, a TRAFFIC OFFLOAD REQUEST REJECT.

[0084] The traffic offload request message may include a user equipment Xn interface identifier (UE XnAP ID) of the traffic offload initiating node and / or one or more F1-C identities, which are used to establish a redundant path for one or more F1-C of an access IAB node, including an IAB node and / or a descendant node of the IAB node, or an IAB node that is to become dual-connected.

[0085] The traffic offload request message may include at least one of the UE XnAP ID of the traffic offload initiating node, a BAP address of the access IAB node, a TNL address, one or more F1-C identification information, one or more F1-U tunnel identification information, IP header information of the F1-C and / or each F1-U tunnel, or quality of service (QoS) information of each F1-U tunnel.

[0086] In at least one aspect, if accepting the traffic offload request for the F1-C and / or F1-U tunnel, the traffic offload request acknowledgement message may include at least one of a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, an identification of the F1-C and / or F1-U tunnel, a newly assigned TNL address for the DU of the access IAB node, a BH RLC channel identifier on a link between the dual-connected IAB node and a second parent node configured for the F1-C and / or F1-U tunnel, a BAP address of the second parent node, a BAP routing identifier in a topology controlled by the second IAB-donor-CU, and a second BAP address of the IAB node, where the traffic offload accepting node is a second IAB-donor-CU. The UE XnAP ID of the traffic offload accepting node is an Xn interface identifier in the second IAB-donor-CU node of the access IAB node.

[0087] In addition, if the second IAB-donor-CU rejects the traffic offload request for all F1-C and F1-U tunnels, the second IAB-donor-CU may send a traffic offload request rejection message to the first IAB-donor-CU, and the traffic offload request rejection message may include the UE XnAP ID of the traffic offload initiation node.

[0088] In at least one aspect, when an IAB node is connected to a first parent node and the IAB node is connected to a second parent node, when the first IAB-donor-CU is a master node (MN), the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or the response rejecting the traffic offload may be included as information elements (IEs) in a message of a secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure of the XnAP.

[0089] In at least one aspect, when the IAB node is connected to a first parent node and the IAB node is not connected to a second parent node, the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or the response rejecting the traffic offload may be included as information elements (IEs) in a message of an XnAP secondary base station node addition preparation (S-NG-RAN node addition preparation) procedure.

[0090] For example, the traffic offload request is included in an S-NODE ADDITION REQUEST message sent by the first IAB-donor-CU to the second IAB-donor-CU. As another example, the response agreeing to the traffic offload is included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU.

[0091] As shown in FIG. 4, the method further includes the following step 403 or step 404.

[0092] Step 403: If the IAB node is connected to a second parent node, the second IAB-donor-CU sends a user equipment context modification request (UE CONTEXT MODIFICATION REQUEST) message to the second parent node to modify the user equipment (UE) context of the mobile terminal (MT) of the IAB node, and establishes at least one bearer.

[0093] Step 404: If the IAB node is not connected to the second parent node, the second IAB-donor-CU sends a user equipment context establishment request (UE CONTEXT SETUP REQUEST) message to the second parent node to establish a UE context of the MT of the IAB node, and sets up at least one bearer.

[0094] As shown in FIG. 4, the method further includes the following steps.

[0095] Step 405: The second IAB-donor-CU configures a BH RLC channel from the IAB node to a second IAB-donor-DU and configures a routing table of the BAP sublayer for a second route required for the IAB node and / or a descendant node of the IAB node.

[0096] As shown in FIG. 4, the method further includes the following steps.

[0097] Step 406: The second IAB-donor-CU sends the address of the second BAP configured for the IAB node to the mobile terminal (MT) of the IAB node.

[0098] For example, in step 406, the second IAB-donor-CU may send a second reconfiguration (RRCReconfiguration) message to the mobile terminal (MT) of the IAB node, the second RRCReconfiguration message including BAP configuration information (bap-Config), where the BAP configuration information includes the address of a second BAP configured for the IAB node.

[0099] In the present invention, according to steps 403 to 403, a second route can be set for the IAB node.

[0100] As shown in FIG. 4, the method further includes the following steps.

[0101] Step 407: The second IAB-donor-CU receives or sends a redundant path release request.

[0102] Step 408: The second IAB-donor-CU sends or receives a redundant path release request acceptance message.

[0103] For example, in step 407, the second IAB-donor-CU receives the redundant path release request sent by the first IAB-donor-CU, and in step 408, the second IAB-donor-CU sends a redundant path release request acceptance message to the first IAB-donor-CU. As another example, in step 407, the second IAB-donor-CU sends a redundant path release request to the first IAB-donor-CU, and in step 408, the second IAB-donor-CU receives the redundant path release request acceptance message sent by the first IAB-donor-CU.

[0104] In at least one aspect, the redundant path release request of step 407 includes a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, a TNL address associated with the F1-C for which the redundant path needs to be released, or UP Transport Layer Information of the F1-U tunnel for which the redundant path needs to be released, where the redundant path is, for example, the second path shown in FIG.

[0105] When the MNs in the first IAB-donor-CU and the second IAB-donor-CU send a redundant path release request, the contents of the redundant path release request and the contents of the redundant path release request acceptance message may be included as IEs in a secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure.

[0106] When performing an IAB node secondary base station node release (S-NG-RAN node Release) procedure, all redundant paths associated with the IAB node (e.g., IAB node 3 in FIG. 2) in the secondary node (SN) topology may be released.

[0107] According to embodiment 2 of the present invention, a redundant path can be established between the first IAB-donor-CU and the second IAB-donor-CU, so that the diversity of paths can be further improved and the needs of load balancing and reducing service interruption can be better met. Also, a topology redundant path between the first IAB-donor-CU and the second IAB-donor-CU can be released.

[0108] The signal transmission / reception method according to the first embodiment and the signal transmission / reception method according to the second embodiment will be described in more detail below with reference to specific examples.

[0109] Example 1 In Example 1, an IAB node (e.g., IAB node 3 in FIG. 2) is in a dual-connected state to two different IAB-donor-CUs, so in Example 1, IAB node 3 is also referred to as a dual-connecting IAB-node.

[0110] Since the F1 interface may be established after the MT of the IAB node is connected to two different donors, the F1 terminating node may be an MN or may be an SN. In the first path, the first IAB-donor-CU (e.g., IAB-donor-CU1 in FIG. 2) is an F1 terminating node, which may be a master node (MN) or a secondary node (SN) in this embodiment. In the second path, the second IAB-donor-CU (e.g., IAB-donor-CU2 in FIG. 2) is a non-F1-terminating node, which may be an SN or an MN in this embodiment.

[0111] 5 is a schematic diagram of an example of a procedure for establishing a second route of an IAB node in the first embodiment. As shown in FIG. 5, the procedure includes the following steps:

[0112] Step 1: IAB-donor-CU1 initiates a traffic offload request (e.g., TRAFFIC OFFLOAD REQUEST) to IAB-donor-CU2, i.e., a request to establish a redundant path for a dual-connected IAB node. If IAB-donor-CU2 rejects, IAB-donor-CU2 directly sends a response rejecting the traffic offload without taking the next step.

[0113] Step 2: If the IAB-donor-CU2 agrees or partially agrees with the traffic offload request, the IAB-donor-CU2 sends a UE CONTEXT MODIFICATION REQUEST message to the IAB-DU of the second parent node of the dual-connectivity IAB node to modify the UE context of the dual-connectivity IAB-MT and set up one or more bearers.

[0114] Step 3: The IAB-DU of the second parent node of the dual connectivity IAB node responds with a UE CONTEXT MODIFICATION RESPONSE message to the IAB-donor-CU2.

[0115] Step 4: If the dual-connected IAB node needs to be assigned a second BAP address, the IAB-donor-CU2 sends a downlink radio link control message transfer (e.g., DL RRC MESSAGE TRANSFER) message to the IAB-DU of the second parent node, which includes the generated RRCReconfiguration message. The RRCReconfiguration message may include a bap-Config that includes the configured second BAP address.

[0116] Step 5: The second parent node forwards the received RRCReconfiguration message to the dual connectivity IAB-MT.

[0117] Step 6: The dual connectivity IAB-MT responds with an RRCReconfigurationComplete message to the second parent node.

[0118] Step 7: The second parent node sends an uplink radio link control message transfer (UL RRC MESSAGE TRANSFER) message to IAB-donor-CU2, where the uplink radio link control message transfer includes the received RRCReconfigurationComplete message.

[0119] Step 8: IAB-donor-CU2 configures the BH RLC channel along the second path from the dual-connecting IAB-node to IAB-donor-DU2 and the routing table of the BAP sublayer (Configuration of BAP route and mapping rules along the second path between dual-connecting IAB-node and the second path IAB-donor-DU via the second parent IAB-node. Step 8 may be performed at an earlier stage, for example immediately after step 2.

[0120] Step 9: IAB-donor-CU2 responds to IAB-donor-CU1 with a message agreeing to traffic offload.

[0121] Step 10: Depending on the content of the response message of IAB-donor-CU2 (e.g., the assigned TNL address, etc.), IAB-donor-CU1 sends a DL RRC MESSAGE TRANSFER message to the IAB-DU of the first parent node, which includes the generated RRCReconfiguration message. This RRCReconfiguration message may include one or more TNL addresses assigned to the dual-connected IAB-DU, which are anchored to the IAB-donor-DU of the second path (e.g., Donor-DU2 in FIG. 2). IAB-donor-CU2 can actively obtain these TNL addresses from Donor-DU2. If IPsec tunnel mode is used to protect F1 and non-F1 traffic, the assigned TNL address is the outer IP address. If a redundant path has already been established for dual-connected IAB nodes F1-C or F1-U, no reallocation is required since the TNL addresses are already assigned.

[0122] Step 11: The first parent node forwards the received RRCReconfiguration message to the dual connectivity IAB-MT.

[0123] Step 12: The dual connectivity IAB-MT responds with an RRCReconfigurationComplete message to the second parent node.

[0124] Step 13: The first parent node sends a UL RRC MESSAGE TRANSFER message to IAB-donor-CU2, which carries the received RRCReconfigurationComplete message.

[0125] Step 15: If new TNL addresses are allocated in step 10, add these addresses to the F1-C associations between the dual-connecting IAB-DU and the IAB-donor-CU1. The IAB-donor-CU1 may configure new UL BH information (uplink backhaul information) for the F1AP message of the second path. The specific procedure may be realized, for example, by the gNB-DU Configuration Update procedure of the F1AP.

[0126] Step 16: The IAB-donor-CU1 may migrate the F1-U tunnel from the IAB-donor-CU1 to the dual connectivity IAB-DU from the first path to the second path via the UE CONTEXT MODIFICATION REQUEST message.

[0127] Step 17: The dual connectivity IAB-DU responds with a UE CONTEXT MODIFICATION RESPONSE message.

[0128] This allows a second path of the dual connectivity IAB node to be established, and uplink user data or downlink user data can be transmitted between the user equipment (UE) and the first IAB-donor-CU via the second path.

[0129] For example, as shown in FIG. 5, in the second path, the transmission order of uplink user data is UE → dual connectivity IAB node → second parent node → intermediate hop IAB node on the second path (Intermediate hop IAB-donor on the second path) → donor distribution unit on the second path (e.g., Donor-DU2 in FIG. 2) → first IAB-donor-CU.

[0130] As another example, as shown in FIG. 5, in the second path, the transmission order of downlink user data is: first IAB-donor-CU → donor distribution unit on the second path (e.g., Donor-DU2 in FIG. 2) → intermediate hop IAB-donor on the second path → second parent node → dual connectivity IAB node → UE.

[0131] In the first embodiment, steps 4-7 are to assign a second BAP address to the dually connected IAB node. The second BAP address may be used for BAP routing configuration on a redundant path (i.e., a second path). The dually connected IAB node needs to associate the BAP address with a master cell group (MCG) / secondary cell group (SCG) or MN / SN. If the RRC Reconfiguration message with the BAP address received by the dually connected node is from an MCG or is received via an SRB1 (SRB: signalling radio bearer), the node associates the received BAP address with an MCG or MN. If the RRC Reconfiguration message with the BAP address received by the dually connected node is from an SCG or is received via an SRB3, the node associates the received BAP address with an SCG or SN.

[0132] Alternatively, the second BAP address may be assigned using another method. For example, steps 4 to 7 may be omitted, and the second BAP address may be included in steps 10 to 13 and sent together with other RRC configuration messages. This requires a change to the existing RRCReconfiguration message format, and there are two possible ways to change it:

[0133] Method 1: A field, such as bap-Address-redundant or bap-Address-second, is added to the bap-Config IE (information element) of the RRC Reconfiguration message to indicate that this field represents a second BAP address.

[0134] Method 2: Change the bap-Address field in the bap-Confg IE of the RRCReconfiguration message to a list such as bap-AddressList, where each entry in the list is a BAP address and its related information, e.g., {bap-Address,'MCG' / 'SCG'} or {bap-Address,iab-donor-DU-BAP-Address}.

[0135] Example 2 In Example 2, an IAB node (e.g., IAB node 3 in FIG. 2) is in a dual-connected state to two different IAB-donor-CUs, so in Example 2, IAB node 3 is also referred to as a dual-connecting IAB-node.

[0136] Example 2 is used to explain how to establish a redundant path between donors for a descendant node of an IAB node (eg, IAB node 4 in FIG. 2).

[0137] Figure 6 is a schematic diagram of an example of a method for establishing a redundant path between donors for a descendant node of an IAB node in Example 2. For simplicity of illustration, possible nodes between the descendant IAB node and the dual-connected IAB node are not shown. The following describes the differences between Figure 6 and Figure 5, but for the same or substantially similar steps, please refer to the description of Example 1.

[0138] As shown in FIG. 6, the establishment procedure includes the following steps:

[0139] Step 1: IAB-donor-CU1 initiates a traffic offload request to IAB-donor-CU2, which includes a request to establish a redundant path for a descendant node of a dual-connected IAB node.

[0140] Steps 4-7: Steps 4-7 are similar to steps 4-7 in embodiment 1, and assign a second BAP address to the dual-connected IAB node if the dual-connected IAB node or other descendant IAB nodes have not previously established a redundant path. Also, if the dual-connected IAB node has already been assigned a second BAP address, steps 4-7 may be skipped.

[0141] Step 8: If necessary, IAB-donor-CU2 configures a BH RLC channel from the dual-connected IAB node to IAB-donor-DU2 for the descendant node in the second path and configures the routing table of the BAP sublayer, similar to the method for dual-connected IAB nodes in Example 1.

[0142] Step 10: Similar to step 10 in FIG. 1, in response to the response message of IAB-donor-CU2, IAB-donor-CU1 configures one or more TNL addresses for descendant IAB nodes, and the one or more TNL addresses are anchored to IAB-donor-DU2.

[0143] Step 14: IAB-donor-CU1 performs configuration of BH RLC channel from dual-connecting IAB-node to descendant access IAB-node and configuration of routing table of BAP sublayer to support routing and BH RLC channel mapping of the second path. IAB-donor-CU1 further performs configuration of BAP routing identifier mapping for dual-connecting IAB-node for BAP routing conversion between two topologies in response to the response message of IAB-donor-CU2 (e.g., sent in step 9). These configurations may be performed at an earlier stage, e.g., immediately after step 10.

[0144] Step 15: If new TNL addresses were allocated in step 10, add these addresses to the F1-C association between the descendant IAB-DU and IAB-donor-CU1. The IAB-donor-CU1 may configure new uplink backhaul information (UL BH information) for F1AP messages of the second path.

[0145] Step 16: IAB-donor-CU1 may migrate the F1-U tunnel from itself to the dual-connected IAB node descendant IAB-DU from the first path to the second path via a UE CONTEXT MODIFICATION REQUEST message.

[0146] Step 17: The descendant IAB-DU responds with a UE CONTEXT MODIFICATION RESPONSE message.

[0147] This allows a second path of a descendant node of the dual connectivity IAB node to be established, and uplink user data or downlink user data can be transmitted between a user equipment (UE) and the first IAB-donor-CU via the second path.

[0148] For example, as shown in FIG. 6, in the second path, the transmission order of uplink user data is UE → descendant node → dual connectivity IAB node → second parent node → intermediate hop IAB node on the second path (Intermediate hop IAB-donor on the second path) → donor distribution unit on the second path (e.g., Donor-DU2 in FIG. 2) → first IAB-donor-CU.

[0149] As another example, as shown in FIG. 6, in the second path, the transmission order of downlink user data is: first IAB-donor-CU → donor distribution unit on the second path (e.g., Donor-DU2 in FIG. 2) → intermediate hop IAB-donor on the second path → second parent node → dual-connected IAB node → descendant node → UE.

[0150] Depending on different implementations, the procedure of establishing a redundant path for a descendant IAB node may be after establishing a redundant path for a doubly connected IAB node, i.e., the procedure of Fig. 6 may be after the procedure of Fig. 5. Alternatively, the procedure of establishing a redundant path for a descendant IAB node may be performed simultaneously with establishing a redundant path for a doubly connected IAB node, i.e., the procedure of Fig. 6 may be performed simultaneously with the procedure of Fig. 5.

[0151] Example 3 In embodiment 3, before the redundant path of an IAB node is established, the IAB node (eg, IAB node 3 in FIG. 2) is a single-connection node, that is, the IAB node is connected to IAB-donor-CU1.

[0152] If IAB-donor-CU1 determines that the traffic in this topology network is overloaded and that traffic offloading is necessary using a network topology managed by another Donor-CU, it performs an operation to add an SN (e.g., IAB-donor-CU2 in Figure 2) to this IAB node, i.e., makes this IAB node dual-connected across donors (i.e., inter-CU), and offloads some of the traffic to the topology of IAB-donor-CU2 to establish a redundant path.

[0153] Figure 7 is a schematic diagram showing how to change an IAB node into a dual-connected node by adding an SN to the IAB node and establish a redundant path. For ease of explanation, the steps of the dual-connected IAB node allocating a second BAP address are not shown in Figure 7 because steps 5 to 7 in Figure 5 may be referred to. The following mainly describes the differences between the procedure shown in Figure 7 and Figure 5, but omits the explanation of the similar parts.

[0154] The procedure of FIG. 7 includes the following steps.

[0155] Step 1: The IAB-MT sends a measurement report (e.g., MeasurementReport) message to the IAB-DU of the first parent node, where the report may be generated based on a measurement configuration (e.g., Measurement Configuration) that this IAB-MT previously received from IAB-donor-CU1.

[0156] Step 2: The IAB-DU of the first parent node sends a UL RRC MESSAGE TRANSFER message to IAB-donor-CU1 to transmit the received Measurement Report.

[0157] Step 3: IAB-donor-CU1 initiates an SN addition request (S-NODE ADDITION REQUEST) message to IAB-donor-CU2, which includes a traffic offload request, i.e., a request to establish a redundant path for an IAB node (e.g., IAB node 3 in FIG. 2). For specific signaling, see Example 4. If IAB-donor-CU2 rejects the request to add an SN, it may send a response to reject traffic offload without performing the following steps. If IAB-donor-CU2 agrees with the request to add an SN and rejects the request for traffic offload, it directly performs the procedure of adding an SN according to existing standards without performing the following steps. The response message includes the content of rejecting traffic offload.

[0158] Step 4: If the traffic offload request is agreed or partially agreed, the IAB-donor-CU2 sends a UE CONTEXT SETUP REQUEST message to the IAB-DU of the second parent node of the IAB node to establish a UE context for the IAB-MT and configure one or more bearers, which may be used for the IAB-MT's own signaling and optional data traffic.

[0159] Step 5: The IAB-DU of the second parent node of the IAB node responds with a UE CONTEXT SETUP RESPONSE message to the IAB-donor-CU2.

[0160] Step 7: IAB-donor-CU2 responds to IAB-donor-CU1 with an S-NODE ADDITION REQUEST ACKNOWLEDGE message, which includes an IE agreeing to traffic offload.

[0161] Step 12: IAB-donor-CU1 sends a secondary node reconfiguration complete (e.g., S-NODE RECONFIGURATION COMPLETE) message to IAB-donor-CU2, indicating that the dual connection configuration to the IAB node has been successfully completed.

[0162] Step 13: The IAB node performs a random access procedure in the IAB-DU of the second parent node.

[0163] The description of other steps in Fig. 7 is the same as that in Example 1. Also, in Fig. 7, if the message in Step 3 includes a request that a redundant path needs to be established for a descendant IAB node, corresponding operations may be performed with reference to Example 2.

[0164] Example 4 Example 4 is used to explain the signaling between IAB-donor-CU1 and IAB-donor-CU2, i.e., XnAP (Xn Application Protocol) procedure. IAB-donor-CU1 sends a traffic offload request to IAB-donor-CU2 to migrate F1-C or one or more F1-U tunnels to a topology-redundant path of IAB-donor--CU2.

[0165] For the first and second embodiments, new dual connectivity related XnAP procedures, such as Traffic Offload procedures, may be added along with new XnAP messages.

[0166] Figure 8 is a schematic diagram of an example of a successful traffic offload procedure. As shown in Figure 8, NG-RAN node 1 (i.e., IAB-donor-CU1) sends a traffic offload request message, such as a TRAFFIC OFFLOAD REQUEST message, to NG-RAN node 2 (i.e., IAB-donor-CU2). NG-RAN node 2 responds with an acceptance or partial acceptance message, such as a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message. Partial acceptance means establishing redundant paths for F1-C or some F1-U tunnels associated with some TNLs.

[0167] Figure 9 is a schematic diagram of an example of a failed traffic offload procedure. As shown in Figure 9, NG-RAN node 1 (i.e., IAB-donor-CU1) sends a traffic offload request message, such as a TRAFFIC OFFLOAD REQUEST message, to NG-RAN node 2 (i.e., IAB-donor-CU2). If NG-RAN node 2 itself has a high traffic load or other failures, it may reject all traffic offload requests so that redundant paths are not established. This traffic offload reject message may be referred to as a TRAFFIC OFFLOAD REQUEST REJECT message, and the message may include a cause of failure.

[0168] The traffic offload request message may include the UE XnAP ID of the traffic offload initiation node and / or the identification information of one or more F1-C. Thus, a redundant path can be established for one or more access IAB nodes. These access IAB nodes may be dual-connected IAB nodes or IAB nodes to be dual-connected, or may be descendant IAB nodes of the dual-connected IAB nodes. The traffic offload request message may further include the BAP address of the access IAB node. The F1-C identification information may be a TNL association or the transmission layer information of the TNL association (e.g., IAB-DU control plane transmission layer address, i.e., TNL address). The TNL association may be explicitly instructed to perform traffic offload of F1-C, or the information of F1-U may not be provided and the TNL association may be implicitly instructed to perform traffic offload of F1-C.

[0169] When accepting the traffic offload request for F1-C, the Traffic Offload Request Acknowledge message may include the UE XnAP ID of the traffic offload initiating node, the UE XnAP ID of the traffic offload accepting node, the identification information of the F1-C, the newly allocated TNL address for the access IAB-DU by IAB-donor-DU2, the BH RLC channel identifier on the link between the dual-connected IAB node configured for the F1-C and the second parent node, the BAP address of the second parent node, the BAP routing identifier (including uplink and downlink) in the topology controlled by CU2, the second BAP address of the possible dual-connected IAB node, etc. Here, the BAP address of the second parent node is used to configure the next hop node of the uplink routing of the redundant path when Donor-CU1 configures a routing table for the dual-connected IAB node. The BAP routing identifier in the topology controlled by Donor-CU2 means the BAP routing identifier of the uplink or downlink from Donor-DU2 to the dual-connected IAB node used when Donor-CU1 configures a BAP routing identifier mapping for the dual-connected IAB node.

[0170] The traffic offload request message may further include identification information of one or more F1-U tunnels, i.e., data radio bearers (DRBs), which indicate the establishment of a redundant path for these F1-U tunnels. The F1-U tunnel identification information may be UP Transport Layer Information, including a transport layer address and a GPRS Tunnelling Protocol-Tunnel Endpoint ID (GTP-TEID). The request message may further include the BAP address, TNL address, IP header information of the access IAB node, QoS information, etc. The IP header information is used to perform IP layer to layer 2 traffic mapping at Donor-DU2, and the QoS information is used to select and configure the BH RLC channel at each hop of the redundant path. The QoS information may be the DRB QoS IE defined in TR38.473, or may be partial information in an IE, such as 5G QoS Identifier (5QI). When accepting or partially accepting the traffic offload request for the F1-U tunnel, the Traffic Offload Request Acknowledge message may further include identification information of the accepted F1-U tunnel, a BH RLC channel identifier on the link between the dual-connected IAB node configured for the F1-U tunnel and the second parent node, and may further include a new TNL address, a BAP address of the second parent node, a BAP routing identifier (including uplink and downlink) in the topology controlled by CU2, a second BAP address of a possible dual-connected IAB node, etc.

[0171] If there is already a dual connection and the MN initiates a traffic offload request, both the request and response message contents may be included as IEs in the S-NG-RAN node modification preparation procedure of the existing XnAP. That is, existing messages such as S-NODE MODIFICATION REQUEST, S-NODE MODIFICATION REQUEST ACKNOWLEDGE, and S-NODE MODIFICATION REJECT are reused. Here, when reusing existing messages, the S-NODE MODIFICATION REQUEST ACKNOWLEDGE message is still used when rejecting all traffic offload requests and agreeing to other modification requests. Only when none of the modification requests are agreed to and none of the traffic offload requests are agreed to or fail, the S-NODE MODIFICATION REJECT message is used.

[0172] In the third embodiment, the contents of these messages may be included as IEs in the existing XnAP S-NG-RAN node addition preparation procedure. That is, existing messages such as S-NODE ADDITION REQUEST, S-NODE ADDITION REQUEST ACKNOWLEDGE, and S-NODE ADDITION REJECT are reused. Here, when reusing existing messages, when all traffic offload requests are rejected and an SN request is agreed to be added, the S-NODE ADDITION REQUEST ACKNOWLEDGE message is still used. Only when the SN cannot be added or fails, the S-NODE MODIFICATION REJECT message is used.

[0173] Example 5 Example 5 is used to explain the procedure of releasing the redundant path between IAB-donor-CU1 and IAB-donor-CU2.

[0174] Both NG-RAN node 1 (i.e., IAB-donor-CU1) and NG-RAN node 2 (i.e., IAB-donor-CU2) may initiate a release procedure for the redundant path. To realize the release procedure, an XnAP procedure related to the new dual connection may be added.

[0175] Both the traffic offload initiator (e.g., IAB-donor-CU1) and the acceptor (e.g., IAB-donor-CU2) may initiate the redundant path release. Figure 10 is a schematic diagram of an example of the redundant path release by the traffic offload initiator, and Figure 11 is a schematic diagram of an example of the redundant path release by the traffic offload acceptor.

[0176] As shown in Figures 10 and 11, different message names may be used to distinguish between a redundant path release initiated by a traffic offload initiator (e.g., IAB-donor-CU1) and a redundant path release initiated by an acceptor (e.g., IAB-donor-CU2). For example, as shown in Figure 10, the traffic offload initiator, i.e., the F1 termination donor node, may send a TRAFFIC OFFLOAD RELEASE REQUEST message to a non-F1 termination donor node, and the non-F1 termination donor node may respond with a TRAFFIC OFFLOAD RELEASE ACKNOWLEDGE message. As shown in Figure 11, the non-F1 termination donor node may send a TRAFFIC OFFLOAD RELEASE REQUIRED message to the F1 termination donor node, and the F1 termination donor node may respond with a TRAFFIC OFFLOAD RELEASE CONFIRM message.

[0177] The TRAFFIC OFFLOAD RELEASE REQUEST / REQUIRED message includes the TNL address associated with the F1-C for which the redundant path needs to be released, or the UP Transport Layer Information of the F1-U tunnel for which the redundant path needs to be released.

[0178] The specific procedure of releasing the redundant path is as follows: If necessary, Donor-CU1 and / or Donor-CU2 release the BAP routing entry for the redundant path, and modify or release the BH RLC channel required for the redundant path. If necessary, Donor-CU1 deletes the mapping information of the associated BAP routing identifier on the dual-connected IAB node.

[0179] When the MN initiates the redundant path release procedure, the contents of the above request and response messages may be included as IEs in the existing S-NG-RAN node modification preparation procedure of the XnAP, i.e., by reusing existing messages such as S-NODE MODIFICATION REQUEST and S-NODE MODIFICATION REQUEST ACKNOWLEDGE.

[0180] When performing the S-NG-RAN node Release procedure, all redundant paths in the SN topology are released.

[0181] <Embodiment 3> The third embodiment of the present invention provides a signal transmission / reception method corresponding to the method of the first embodiment, at least for the same problem as the first embodiment. The signal transmission / reception method according to the third embodiment of the present invention is applied to an IAB node, for example, the IAB node 3 in FIG.

[0182] 12 is a schematic diagram of an example of a signal transmitting and receiving method according to embodiment 3. As shown in FIG. 12, the method includes the following steps:

[0183] Step 1201: Receive a first RRC reconfiguration message sent by a first IAB-donor-CU.

[0184] Step 1202: Send an RRC reconfiguration complete message to the first IAB-donor-CU.

[0185] Wherein, the first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to a first IAB-donor-CU, the first RRC reconfiguration message including at least one TNL address assigned to a DU of the IAB node, the TNL address being anchored to a second IAB-donor-DU in the topology of the second IAB-donor-CU.

[0186] The BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a field to indicate the second BAP address configured for the IAB node, or the BAP address field in the BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a list, and each entry in the list is a BAP address and its associated information.

[0187] The RRC reconfiguration complete (e.g., RRCReconfigurationComplete) message in step 1202 is used to indicate that the IAB node has received the first RRC reconfiguration message, and the RRC reconfiguration complete message may further indicate that the IAB node has completed the reconfiguration.

[0188] According to steps 1201 and 1202, a redundant path across the donor can be established for the IAB node.

[0189] As shown in FIG. 12, the method further includes the following steps.

[0190] Step 1203: The IAB node receives a second RRC Reconfiguration message sent by a second IAB-donor-CU.

[0191] Step 1204: The IAB node sends a reconfiguration complete (RRCReconfigurationComplete) message to the second IAB-donor-CU.

[0192] In step 1203, a second RRC Reconfiguration message includes BAP configuration information (bap-Config), which includes a second BAP address configured for the IAB node. In step 1204, a reconfiguration complete (RRCReconfigurationComplete) message is used to indicate that the IAB node has received the second RRC Reconfiguration message.

[0193] As shown in FIG. 12, the method further includes the following steps.

[0194] Step 1205: The IAB node associates the second BAP address with a master cell group (MCG) / secondary cell group (SCG) or a master node (MN) / secondary node (SN).

[0195] For example, if the second RRC Reconfiguration message having a second BAP address received by the IAB node is from an MCG or received via a signalling radio bearer 1 (SRB), the second BAP address is associated with an MCG or an MN, and if the second RRC Reconfiguration message having a second BAP address received by the IAB node is from an SCG or received via an SRB3, the second BAP address is associated with an SCG or an SN.

[0196] <Embodiment 4> The fourth embodiment of the present invention provides a signal transmission / reception method corresponding to the method of the first embodiment, at least for the same problem as the first embodiment. The signal transmission / reception method according to the fourth embodiment of the present invention is applied to a descendant node of an IAB node, for example, the IAB node 4 in FIG.

[0197] 13 is a schematic diagram of an example of a signal transmitting and receiving method according to embodiment 3. As shown in FIG. 13, the method includes the following steps:

[0198] Step 1301: Receive a first RRC reconfiguration message sent by a first IAB-donor-CU.

[0199] Step 1302: Send an RRC reconfiguration complete message to the first IAB-donor-CU.

[0200] Here, the first RRC reconfiguration message in step 1301 is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to a first IAB-donor-CU, the first RRC reconfiguration message including at least one TNL address assigned to a DU of the descendant node, the TNL address being anchored to a second IAB-donor-DU in the topology of the second IAB-donor-CU.

[0201] Here, the RRCReconfigurationComplete message in step 1302 is used to indicate that the descendant node has received the first RRC reconfiguration message, and the RRCReconfigurationComplete message may further indicate that the descendant node has completed reconfiguration.

[0202] According to embodiment 4, redundant paths across donors can be established for descendant nodes of IAB nodes.

[0203] <Embodiment 5> An embodiment of the present invention provides a signal transmission and reception device, which is applied to a first IAB-donor-CU. The device may be a first Donor-CU or a part of the first Donor-CU. The device corresponds to the method of embodiment 1.

[0204] 14 is a schematic diagram of an example of a signal transmission / reception device according to an embodiment of the present invention. As shown in FIG. 14, a signal transmission / reception device 1400 includes a first transmission / reception unit 1401.

[0205] The first transceiver 1401 is configured to send a traffic offload request to a second IAB-donor-CU and receive a response agreeing to the traffic offload or a response rejecting the traffic offload sent by the second IAB-donor-CU.

[0206] In at least one aspect, the first transceiver 1401 is configured to transmit a first RRC reconfiguration message to the IAB node and / or a descendant IAB node of the IAB node in response to a response agreeing to the traffic offload.

[0207] Here, the first RRC reconfiguration message includes at least one TNL address assigned to the IAB node and / or a DU of a descendant node of the IAB node, respectively, the TNL address being anchored to a second IAB-donor-DU in the topology of the second IAB-donor-CU, the IAB node being connected to a first parent node, which is a node in the topology of the first IAB-donor-CU, the IAB node being already connected or to be connected to a second parent node, which is a node in the topology of the second IAB-donor-CU.

[0208] In at least one aspect, a BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a field to indicate a second BAP address configured for the IAB node, or a BAP address field in the BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a list, each entry in the list being a BAP address and its associated information.

[0209] In at least one aspect, the first transceiver is configured to add a new TNL address, when assigned, to an F1-C association between a DU of the IAB node and / or a descendant node of the IAB node and the first IAB-donor-CU.

[0210] In at least one aspect, the traffic offload request includes a request to establish a redundant path for the IAB node and / or a descendant node of the IAB node.

[0211] In at least one aspect, the first transceiver 1401 is configured to configure a BH RLC channel from the IAB node to a descendant node of the IAB node and configure a routing table of a BAP sublayer for a first IAB-donor-CU to support routing and BH RLC channel mapping of a second path.

[0212] In at least one aspect, the first transceiver 1401 is configured to configure a BAP routing identifier mapping for the IAB node in response to a response from the first IAB-donor-CU agreeing to the traffic offload.

[0213] In at least one aspect, the first transceiver 1401 is configured to migrate, by a first IAB-donor-CU, an F1-U tunnel from the first IAB-donor-CU to a DU of the IAB node and / or a descendant node of the IAB node from a first path to a second path via a user equipment context modification request (UE CONTEXT MODIFICATION REQUEST) message or a user equipment context establishment request (UE CONTEXT SETUP REQUEST) message.

[0214] In at least one aspect, the response agreeing to the traffic offload indicates at least partially accepting the traffic offload request, where at least partially accepting the traffic offload request means establishing redundant paths for F1-C or some F1-U tunnels associated with some TNLs.

[0215] In at least one aspect, an IAB node is connected to a first parent node, which is connected to a second parent node, which is a node in a topology of the first IAB-donor-CU, and which is a node in a topology of the second IAB-donor-CU, the traffic offload request is included in a TRAFFIC OFFLOAD REQUEST message, a response agreeing to the traffic offload is included in a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message, and a response rejecting the traffic offload is included in a TRAFFIC OFFLOAD REQUEST REJECT message.

[0216] In at least one aspect, the traffic offload request message may include a traffic offload initiating node's user equipment Xn interface identifier (UE XnAP ID) and / or one or more F1-C identities that are used to establish redundant paths for one or more F1-C of an access IAB node, including an IAB node and / or a descendant node of the IAB node, or an IAB node that is becoming dual-connected.

[0217] In at least one aspect, the traffic offload request message includes at least one of an identifier at the Xn interface of the user equipment of the traffic offload initiating node (UE XnAP ID), a BAP address of the access IAB node, a TNL address, one or more F1-C identification information, one or more F1-U tunnel identification information, IP header information of the F1-C and / or each F1-U tunnel, or QoS information of each F1-U tunnel.

[0218] In at least one aspect, if a traffic offload request for an F1-C and / or F1-U tunnel is accepted, the TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message includes at least one of a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, an identification information of the F1-C and / or F1-U tunnel, a newly assigned TNL address for the DU of the access IAB node, a BH RLC channel identifier on the link between the dual-connected IAB node and a second parent node configured for the F1-C and / or F1-U tunnel, a BAP address of the second parent node, a BAP routing identifier in a topology controlled by the second IAB-donor-CU, and a second BAP address of the IAB node.

[0219] In at least one aspect, if the traffic offload request for all F1-C and F1-U tunnels is rejected, the TRAFFIC OFFLOAD REQUEST REJECT message includes the UE XnAP ID of the traffic offload initiating node.

[0220] In at least one aspect, an IAB node is connected to a first parent node, which is connected to a second parent node, which is a node in the topology of the first IAB-donor-CU, and which is a node in the topology of the second IAB-donor-CU.

[0221] The first IAB-donor-CU is a master node (MN), and the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or rejecting the traffic offload are included as information elements (IEs) in a message of the XnAP secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure.

[0222] In at least one aspect, an IAB node is connected to a first parent node, the IAB node is not connected to a second parent node, the first parent node is a node in the topology of the first IAB-donor-CU, and the second parent node is a node in the topology of the second IAB-donor-CU.

[0223] The contents of the traffic offload request and the contents of the response agreeing to the traffic offload or rejecting the traffic offload are included as information elements (IEs) in a message of the XnAP secondary base station node addition preparation (S-NG-RAN node addition preparation) procedure.

[0224] In at least one aspect, the traffic offload request is included in a Secondary Node Addition Request (S-NODE ADDITION REQUEST) message sent by the first IAB-donor-CU to the second IAB-donor-CU.

[0225] In at least one aspect, the response agreeing to the traffic offload is included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU.

[0226] In at least one aspect, the response denying the traffic offload is included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU.

[0227] In at least one aspect, the first transceiver 1401 is configured for the first IAB-donor-CU to send or receive a redundant path release request and for the first IAB-donor-CU to receive or send a redundant path release request acceptance message.

[0228] In at least one aspect, the redundant path release request includes a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, a TNL address associated with the F1-C for which the redundant path needs to be released, or user plane transport layer information (UP Transport Layer Information) of the F1-U tunnel for which the redundant path needs to be released.

[0229] In at least one aspect, the redundant path release request includes a UE XnAP ID of a traffic offload initiating node and a UE XnAP ID of a traffic offload accepting node.

[0230] In at least one aspect, when an MN in the first IAB-donor-CU and the second IAB-donor-CU transmits a redundant path release request, the contents of the redundant path release request and the contents of the redundant path release request acceptance message are included as IEs in a secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure.

[0231] In at least one aspect, when an IAB node secondary base station node release procedure is performed, all redundant paths associated with the IAB node in the SN topology are released.

[0232] For a detailed description of the first transceiver unit 1401, please refer to the description of the method in embodiment 1.

[0233] <Embodiment 6> An embodiment of the present invention provides a signal transmitting and receiving device, which is applied to a second IAB-donor-CU. The device may be a second Donor-CU, or may be an element or component configured in the second Donor-CU. The device corresponds to the method of embodiment 2.

[0234] 15 is a schematic diagram of an example of a signal transmitting / receiving device according to embodiment 6. As shown in FIG.

[0235] The second transceiver 1501 is configured to receive a traffic offload request sent by a first IAB-donor-CU, and send a response to the first IAB-donor-CU agreeing to the traffic offload or rejecting the traffic offload.

[0236] In at least one aspect, the traffic offload request includes a request to establish a redundant path for the IAB node and / or a descendant node of the IAB node.

[0237] In at least one aspect, the second transceiver 1501 is configured to, when the IAB node is connected to a second parent node, send a User Equipment Context Modification Request (UE CONTEXT MODIFICATION REQUEST) message to the second parent node to modify a User Equipment (UE) context of a mobile terminal (MT) of the IAB node and set up at least one bearer, where the second parent node is a node in the topology of the second IAB-donor-CU.

[0238] In at least one aspect, the second transceiver 1501 is configured to, if the IAB node is not connected to a second parent node, send a user equipment context establishment request (UE CONTEXT SETUP REQUEST) message to the second parent node, so that the second IAB-donor-CU establishes a UE context for an MT of the IAB node, and sets up at least one bearer.

[0239] Here, the second parent node is a node in the topology of the second IAB-donor-CU.

[0240] In at least one aspect, the second transceiver 1501 is configured for the second IAB-donor-CU to send a second reconfiguration (RRCReconfiguration) message to a mobile terminal (MT) of the IAB node, the second RRCReconfiguration message including BAP configuration information (bap-Config), the BAP configuration information including an address of a second BAP configured for the IAB node.

[0241] In at least one aspect, the second transceiver 1501 is configured for the second IAB-donor-CU to configure a BH RLC channel from the IAB node to a second IAB-donor-DU and configure a routing table of the BAP sublayer for a second route required for the IAB node and / or a descendant node of the IAB node.

[0242] The second IAB-donor-DU is within the topology of the second IAB-donor-CU.

[0243] In at least one aspect, the response agreeing to the traffic offload indicates at least partially accepting the traffic offload request, where at least partially accepting the traffic offload request means establishing redundant paths for F1-C or some F1-U tunnels associated with some TNLs.

[0244] In at least one aspect, an IAB node is connected to a first parent node, which is connected to a second parent node, which is a node in the topology of the first IAB-donor-CU, and which is a node in the topology of the second IAB-donor-CU.

[0245] The traffic offload request is included in a TRAFFIC OFFLOAD REQUEST message, a response agreeing to the traffic offload is included in a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message, and a response rejecting the traffic offload is included in a TRAFFIC OFFLOAD REQUEST REJECT message.

[0246] In at least one aspect, the traffic offload request message may include a traffic offload initiating node's user equipment Xn interface identifier (UE XnAP ID) and / or one or more F1-C identities that are used to establish redundant paths for one or more F1-C of an access IAB node, including an IAB node and / or a descendant node of the IAB node, or an IAB node that is becoming dual-connected.

[0247] In at least one aspect, the traffic offload request message includes at least one of an identifier at the Xn interface of the user equipment of the traffic offload initiating node (UE XnAP ID), a BAP address of the access IAB node, a TNL address, one or more F1-C identification information, one or more F1-U tunnel identification information, IP header information of the F1-C and / or each F1-U tunnel, or QoS information of each F1-U tunnel.

[0248] In at least one aspect, if a traffic offload request for an F1-C and / or F1-U tunnel is accepted, the TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message includes at least one of a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, an identification information of the F1-C and / or F1-U tunnel, a newly assigned TNL address for the DU of the access IAB node, a BH RLC channel identifier on the link between the dual-connected IAB node and a second parent node configured for the F1-C and / or F1-U tunnel, a BAP address of the second parent node, a BAP routing identifier in a topology controlled by the second IAB-donor-CU, and a second BAP address of the IAB node.

[0249] In at least one aspect, if the traffic offload request for all F1-C and F1-U tunnels is rejected, the TRAFFIC OFFLOAD REQUEST REJECT message includes the UE XnAP ID of the traffic offload initiating node, and preferably includes the UE XnAP ID of the traffic offload rejecting node.

[0250] In at least one embodiment, an IAB node is connected to a first parent node, which is connected to a second parent node, which is a node in the topology of the first IAB-donor-CU, and which is a node in the topology of the second IAB-donor-CU.

[0251] The first IAB-donor-CU is a master node (MN), and the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or rejecting the traffic offload are included as information elements (IEs) in a message of the XnAP secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure.

[0252] In at least one aspect, an IAB node is connected to a first parent node, the IAB node is not connected to a second parent node, the first parent node is a node in the topology of the first IAB-donor-CU, and the second parent node is a node in the topology of the second IAB-donor-CU.

[0253] The contents of the traffic offload request and the contents of the response agreeing to the traffic offload or rejecting the traffic offload are included as information elements (IEs) in a message of the XnAP secondary base station node addition preparation (S-NG-RAN node addition preparation) procedure.

[0254] In at least one aspect, the traffic offload request is included in a Secondary Node Addition Request (S-NODE ADDITION REQUEST) message sent by the first IAB-donor-CU to the second IAB-donor-CU.

[0255] In at least one aspect, the response agreeing to the traffic offload is included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU.

[0256] In at least one aspect, the second transceiver 1501 is configured for the second IAB-donor-CU to receive or transmit a redundant path release request and for the second IAB-donor-CU to transmit or receive a redundant path release request acceptance message.

[0257] In at least one aspect, the redundant path release request includes a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, a TNL address associated with the F1-C for which the redundant path needs to be released, or user plane transport layer information (UP Transport Layer Information) of the F1-U tunnel for which the redundant path needs to be released.

[0258] In at least one aspect, when an MN in the first IAB-donor-CU and the second IAB-donor-CU transmits a redundant path release request, the contents of the redundant path release request and the contents of the redundant path release request acceptance message are included as IEs in a secondary base station node modification preparation (S-NG-RAN node modification preparation) procedure.

[0259] In at least one aspect, when an IAB node secondary base station node release procedure is performed, all redundant paths associated with the IAB node in the SN topology are released.

[0260] For a detailed description of the second transceiver unit 1501, please refer to the description of the method in embodiment 2.

[0261] <Embodiment 7> An embodiment of the present invention provides a signal transmitting and receiving device, which is applied to an IAB node. The device may be an IAB node, or an element or component configured in the IAB node. The device corresponds to the method of embodiment 3.

[0262] 16 is a schematic diagram of an example of a signal transmitting / receiving device according to embodiment 7. As shown in FIG.

[0263] The third transceiver 1601 is configured to receive a first RRC reconfiguration message sent by the first IAB-donor-CU, and send an RRC reconfiguration complete message to the first IAB-donor-CU.

[0264] In at least one aspect, the first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to the first IAB-donor-CU. The first RRC reconfiguration message includes at least one TNL address assigned to a DU of the IAB node, the TNL address being anchored to a second IAB-donor-DU in a topology of the second IAB-donor-CU. Here, the RRCReconfigurationComplete message is used to indicate that the IAB node has received the first RRC reconfiguration message. The RRCReconfigurationComplete message may further indicate that the IAB node has completed the reconfiguration.

[0265] In at least one aspect, the third transceiver unit 1601 is configured for the IAB node to receive a second RRC Reconfiguration message sent by the second IAB-donor-CU, the second RRC Reconfiguration message including BAP configuration information (bap-Config), the BAP configuration information including a second BAP address configured for the IAB node, and for the IAB node to send a reconfiguration complete (RRCReconfigurationComplete) message to the second IAB-donor-CU.

[0266] Here, the reconfiguration complete (RRCReconfigurationComplete) message is used to indicate that the IAB node has received the second RRC Reconfiguration message.

[0267] In at least one aspect, the third transceiver 1601 is configured for the IAB node to associate the second BAP address with a master cell group (MCG) / secondary cell group (SCG) or a master node (MN) / secondary node (SN).

[0268] In at least one aspect, if the second RRC Reconfiguration message having the second BAP address received by the IAB node is from an MCG or received via a signalling radio bearer 1 (SRB), the second BAP address is associated with an MCG or an MN, and if the second RRC Reconfiguration message having the second BAP address received by the IAB node is from an SCG or received via an SRB3, the second BAP address is associated with an SCG or an SN.

[0269] In at least one aspect, a BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a field to indicate a second BAP address configured for the IAB node, or a BAP address field in the BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a list, each entry in the list being a BAP address and its associated information.

[0270] For a detailed description of the third transceiver unit 1601, please refer to the description of the method in embodiment 3.

[0271] <Embodiment 8> An embodiment of the present invention provides a signal transmitting and receiving device. The device is applied to a descendant node of an IAB node. The device may be a descendant node of the IAB node, or may be an element or component configured in the descendant node of the IAB node. The device corresponds to the method of embodiment 4.

[0272] 17 is a schematic diagram of an example of a signal transmitting / receiving device according to embodiment 8. As shown in FIG.

[0273] The fourth transceiver 1701 is configured to receive a first RRC reconfiguration message sent by the first IAB-donor-CU, and send an RRC reconfiguration complete message to the first IAB-donor-CU.

[0274] Wherein, the first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to the first IAB-donor-CU. The first RRC reconfiguration message includes at least one TNL address assigned to a DU of the descendant node, and the TNL address is anchored to a second IAB-donor-DU in the topology of the second IAB-donor-CU. Herein, the RRCReconfigurationComplete message is used to indicate that the descendant node has received the first RRC reconfiguration message. In addition, the RRCReconfigurationComplete message may further indicate that the descendant node has completed the reconfiguration.

[0275] For a detailed description of the fourth transceiver unit 1701, please refer to the description of the method in embodiment 4.

[0276] <Embodiment 9> An embodiment of the present invention further provides a communication system, which may be referred to in FIG.

[0277] In some aspects, a communication system may include a first IAB-donor-CU, a second IAB-donor-CU, an IAB node, and a descendant node of the IAB node.

[0278] The first IAB-donor-CU includes a signal transmission / reception device 1400 according to the fifth embodiment.

[0279] The second IAB-donor-CU includes a signal transmitting / receiving device 1500 according to the sixth embodiment.

[0280] The IAB node includes a signal transmitting / receiving device 1600 according to the seventh embodiment.

[0281] A descendant node of the IAB node includes a signal transmitting / receiving device 1700 according to the eighth embodiment.

[0282] Here, the access backhaul integrated node (IAB-node) may include an IAB-MT functional unit and an IAB-DU functional unit. Here, the IAB-MT functional unit may have a configuration similar to that of a terminal device. The IAB-DU functional unit, the first IAB-donor CU, and the second IAB-donor CU may have units similar to those of a network device.

[0283] Fig. 18 is a schematic diagram of a configuration of a network device according to an embodiment of the present invention. As shown in Fig. 18, the network device 1800 may include a processor 1810 (e.g., a central processing unit CPU) and a memory 1820. The memory 1820 is connected to the processor 1810. The memory 1820 may store various data, and further stores an information processing program 1830, and executes the program 1830 under the control of the processor 1810.

[0284] For example, the processor 1810 may be configured to execute a program for implementing a method performed by an IAB-donor CU in embodiment 1 or embodiment 2, or a method performed by an IAB-DU in embodiment 3 or embodiment 4.

[0285] Also, as shown in FIG. 18, the network device 1800 may further include a transceiver 1840 and an antenna 1850. Here, the functions of the above units are the same as those of the conventional technology, and the description thereof will be omitted here. It is not necessary for the network device 1800 to include all the units shown in FIG. 18. Also, the network device 1800 may further include units not shown in FIG. 18, and may refer to the conventional technology. Also, the IAB-donor-CU and the IAB-donor-DU may exist in one node and become one network device IAB-donor, or may be separated into two nodes to realize different functions of the network device, and may refer to the conventional technology.

[0286] FIG. 19 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in FIG. 19, the terminal device 1900 may include a processor 1910 and a memory 1920. The memory 1920 stores data and programs and is connected to the processor 1910. Note that this figure is exemplary, and other types of structures may be used to supplement or replace this structure to realize communication functions or other functions. For example, the processor 1910 may be configured to execute a program for implementing the method performed by the IAB-MT in embodiment 3 or embodiment 4.

[0287] As shown in Fig. 19, the terminal device 1900 may further include a communication module 1930, an input unit 1940, a display 1950, and a power source 1960. Here, the functions of the above units are similar to those of the conventional technology, and the description thereof will be omitted here. It is not necessary for the terminal device 1900 to include all the units shown in Fig. 19. In addition, the terminal device 1900 may further include units not shown in Fig. 19, and may refer to the conventional technology.

[0288] In an embodiment of the present invention, a computer program is further provided, which, when executed in a Donor CU, causes the Donor CU to perform the method according to embodiment 1 or embodiment 2.

[0289] An embodiment of the present invention further provides a storage medium having a computer program stored therein, the storage medium causing the Donor CU to perform the method according to embodiment 1 or embodiment 2 when the computer program is executed.

[0290] In an embodiment of the present invention, there is further provided a computer program, which, when executed in an IAB or its descendant node, causes the IAB or its descendant node to execute the signal transmission and reception method described in embodiment 3 or embodiment 4.

[0291] An embodiment of the present invention further provides a storage medium having a computer program stored therein, the storage medium causing the IAB or its descendant node to execute the signal transmission and reception method described in embodiment 3 or embodiment 4 when the computer program is executed.

[0292] The above-mentioned apparatus and method of the present invention may be realized by hardware or by a combination of hardware and software.The present invention relates to a computer readable program which, when executed by a logic unit, causes the logic unit to realize the above-mentioned apparatus or components, or to realize the above-mentioned various methods or steps.The present invention relates to a storage medium for storing the above-mentioned program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0293] Each processing method in each device described with reference to the embodiments of the present invention may be implemented by hardware, a software module executed by a processor, or a combination of both. For example, one or more of the functional block diagrams shown in the drawings, or one or more combinations of the functional block diagrams, may correspond to each software module in a computer program flow, or each hardware module. These software modules may correspond to each step shown in the drawings. These hardware modules may be realized by implementing these software modules in hardware, for example, using a field programmable gate array (FPGA).

[0294] The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium known to those skilled in the art. The storage medium may be connected to the processor such that the processor reads information from and / or writes information to the storage medium, or the storage medium may be a component of the processor. The processor and the storage medium may be located in an ASIC. The software module may be stored in the memory of the mobile terminal, or in a memory card inserted in the mobile terminal. For example, if the device (e.g., a mobile terminal) uses a MEGA-SIM card or a large capacity flash memory device with a relatively large capacity, the software module may be stored in the MEGA-SIM card or the large capacity flash memory device.

[0295] One or more of the functional blocks and / or one or more combinations of functional blocks in the functional block diagrams illustrated in the drawings may be implemented with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or any suitable combination thereof to perform the functions described herein. One or more of the functional blocks and / or one or more combinations of functional blocks in the functional block diagrams illustrated in the drawings may be implemented with, for example, a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, one or more microprocessors in combination with a DSP communication, or any other configuration.

[0296] Although the present invention has been described above with reference to specific embodiments, the above description is merely illustrative and does not limit the scope of protection of the present invention. Various modifications and changes may be made to the present invention without departing from the spirit and principles of the present invention, and these modifications and changes are also within the scope of the present invention.

[0297] Furthermore, the following supplementary notes are disclosed regarding the embodiments including the above-mentioned examples.

[0298] First IAB-donor-CU method: (Appendix 1) A signal transmission / reception method applied to a first access backhaul integrated node donor aggregation unit (IAB-donor-CU), comprising: sending a traffic offload request to a second IAB-donor-CU; receiving a response agreeing to the traffic offload or a response rejecting the traffic offload sent by the second IAB-donor-CU. (Appendix 2) In response to the response agreeing to the traffic offload, sending a first RRC reconfiguration message to the IAB node and / or a descendant IAB node of the IAB node; The first RRC reconfiguration message includes at least one TNL address assigned to a DU of the IAB node and / or a descendant node of the IAB node, respectively, and the TNL address is anchored to a second IAB-donor-DU in the topology of the second IAB-donor-CU; 2. The method of claim 1, wherein the IAB node is connected to a first parent node, the first parent node being a node in the topology of the first IAB-donor-CU, and the IAB node is already connected or will be connected to a second parent node, the second parent node being a node in the topology of the second IAB-donor-CU. (Appendix 3) a BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a field for indicating a second BAP address configured for the IAB node; or 3. The method of claim 2, wherein a BAP address field in a BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a list, and each entry in the list is a BAP address and its associated information. (Appendix 4) The method of claim 2, further comprising the step of: when a new TNL address is assigned, adding the new TNL address to an F1-C association between the DU of the IAB node and / or a descendant node of the IAB node and the first IAB-donor-CU. (Appendix 5) 2. The method of claim 1, wherein the traffic offload request includes a request to establish a redundant path for an IAB node and / or a descendant node of the IAB node. (Appendix 6) The method of claim 5, wherein the first IAB-donor-CU configures a BH RLC channel from the IAB node to a descendant node of the IAB node and configures a routing table of a BAP sublayer to support routing and BH RLC channel mapping of a second path. (Appendix 7) The method of claim 5, further comprising: configuring a BAP routing identifier mapping for the IAB node in response to the first IAB-donor-CU agreeing to the traffic offload. (Appendix 8) The method of claim 5, further comprising a step of a first IAB-donor-CU migrating an F1-U tunnel from the first IAB-donor-CU to a DU of the IAB node and / or a descendant node of the IAB node from a first path to a second path via a user equipment context modification request (UE CONTEXT MODIFICATION REQUEST) message or a user equipment context establishment request (UE CONTEXT SETUP REQUEST) message. (Appendix 9) the traffic offload agreeing response indicates at least partial acceptance of the traffic offload request; 2. The method of claim 1, wherein at least partially accepting the traffic offload request means establishing redundant paths for F1-C or F1-U tunnels associated with some TNLs. (Appendix 10) an IAB node is connected to a first parent node, the IAB node is connected to a second parent node, the first parent node being a node in the topology of the first IAB-donor-CU, and the second parent node being a node in the topology of the second IAB-donor-CU; 2. The method of claim 1, wherein the traffic offload request is included in a TRAFFIC OFFLOAD REQUEST message, a response agreeing to the traffic offload is included in a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message, and a response rejecting the traffic offload is included in a TRAFFIC OFFLOAD REQUEST REJECT message. (Appendix 11) The traffic offload request message: The method of claim 10, comprising at least one of an identifier at the Xn interface of the user equipment of the traffic offload initiation node (UE XnAP ID), a BAP address of the access IAB node, a TNL address, one or more F1-C identification information, one or more F1-U tunnel identification information, IP header information of the F1-C and / or each F1-U tunnel, or QoS information of each F1-U tunnel. (Appendix 12) If the traffic offload request for the F1-C and / or F1-U tunnel is accepted, the TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message may include: 12. The method of claim 11, further comprising at least one of a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, identification information of the F1-C and / or F1-U tunnel, a newly allocated TNL address for a DU of an access IAB node, a BH RLC channel identifier on a link between a dual-connected IAB node and a second parent node configured for the F1-C and / or F1-U tunnel, a BAP address of a second parent node, a BAP routing identifier in a topology controlled by the second IAB-donor-CU, and a second BAP address of the IAB node. (Appendix 13) The method of claim 11, wherein if the traffic offload request for all F1-C and F1-U tunnels is rejected, the traffic offload request reject message includes the UE XnAP ID of the traffic offload initiation node. (Appendix 14) an IAB node is connected to a first parent node, the IAB node is connected to a second parent node, the first parent node being a node in the topology of the first IAB-donor-CU, and the second parent node being a node in the topology of the second IAB-donor-CU; The method described in Supplementary Note 1, wherein the first IAB-donor-CU is a master node (MN), and the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or the response rejecting the traffic offload are included as information elements (IEs) in a message of a secondary base station node modification preparation (S-NG-RAN node Modification Preparation) procedure of an XnAP. (Appendix 15) an IAB node is connected to a first parent node, the IAB node is not connected to a second parent node, the first parent node is a node in the topology of the first IAB-donor-CU, and the second parent node is a node in the topology of the second IAB-donor-CU; The method described in Supplementary Note 1, in which the content of the traffic offload request and the content of the response agreeing to the traffic offload or the response rejecting the traffic offload are included as information elements (IEs) in a message of a secondary base station node addition preparation (S-NG-RAN node addition preparation) procedure of the XnAP. (Appendix 16) 16. The method of claim 15, wherein the traffic offload request is included in a Secondary Node Addition Request (S-NODE ADDITION REQUEST) message sent by the first IAB-donor-CU to the second IAB-donor-CU. (Appendix 17) 16. The method of claim 15, wherein the response agreeing to the traffic offload is included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU. (Appendix 18) The first IAB-donor-CU sends or receives a redundant path release request; The method of claim 1, further comprising the step of the first IAB-donor-CU receiving or sending a redundant path release request acceptance message. (Appendix 19) The method described in Supplementary Note 18, wherein the redundant path release request includes a UE XnAP ID of a traffic offload initiating node, a UE XnAP ID of a traffic offload accepting node, a TNL address associated with an F1-C for which the redundant path needs to be released, or user plane transport layer information (UP Transport Layer Information) of an F1-U tunnel for which the redundant path needs to be released. (Appendix 20) When the MN in the first IAB-donor-CU and the second IAB-donor-CU transmits a redundant path release request, The method according to claim 18, wherein the content of the redundant path release request and the content of the redundant path release request acceptance message are included as IEs in a secondary base station node modification preparation (S-NG-RAN node Modification Preparation) procedure. (Appendix 21) The method described in Supplementary Note 1, wherein when performing a secondary base station node release (S-NG-RAN node Release) procedure for an IAB node, all redundant paths related to the IAB node in the SN topology are released.

[0299] Second IAB-donor-CU method: (Appendix 1) A signal transmission / reception method applied to a second access backhaul integrated node donor aggregation unit (IAB-donor-CU), comprising: receiving a traffic offload request sent by a first IAB-donor-CU; sending a response to the first IAB-donor-CU agreeing to the traffic offload or a response to reject the traffic offload. (Appendix 2) 2. The method of claim 1, wherein the traffic offload request includes a request to establish a redundant path for an IAB node and / or a descendant node of the IAB node. (Appendix 3) If the IAB node is connected to a second parent node, the second IAB-donor-CU sends a user equipment context modification request (UE CONTEXT MODIFICATION REQUEST) message to the second parent node to modify a user equipment (UE) context of a mobile terminal (MT) of the IAB node, and sets up at least one bearer; 2. The method of claim 1, wherein the second parent node is a node in a topology of the second IAB-donor-CU. (Appendix 4) If the IAB node is not connected to a second parent node, the second IAB-donor-CU sends a User Equipment Context Establishment Request (UE CONTEXT SETUP REQUEST) message to the second parent node to establish a UE context for the MT of the IAB node, and sets up at least one bearer; 2. The method of claim 1, wherein the second parent node is a node in a topology of the second IAB-donor-CU. (Appendix 5) The method of claim 3 or 4, further comprising a step of: the second IAB-donor-CU sending a second reconfiguration (RRCReconfiguration) message to a mobile terminal (MT) of the IAB node, the second RRCReconfiguration message including BAP configuration information (bap-Config), the BAP configuration information including an address of a second BAP configured for the IAB node. (Appendix 6) The second IAB-donor-CU further includes a step of configuring a BH RLC channel from the IAB node to a second IAB-donor-DU and configuring a routing table of a BAP sublayer for a second route required for the IAB node and / or a descendant node of the IAB node; 5. The method of claim 3, wherein the second IAB-donor-DU is within the topology of the second IAB-donor-CU. (Appendix 7) the traffic offload agreeing response indicates at least partial acceptance of the traffic offload request; 2. The method of claim 1, wherein at least partially accepting the traffic offload request means establishing redundant paths for F1-C or F1-U tunnels associated with some TNLs. (Appendix 8) an IAB node is connected to a first parent node, the IAB node is connected to a second parent node, the first parent node being a node in the topology of the first IAB-donor-CU, and the second parent node being a node in the topology of the second IAB-donor-CU; 2. The method of claim 1, wherein the traffic offload request is included in a TRAFFIC OFFLOAD REQUEST message, a response agreeing to the traffic offload is included in a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message, and a response rejecting the traffic offload is included in a TRAFFIC OFFLOAD REQUEST REJECT message. (Appendix 9) The traffic offload request message: The method described in Supplementary Note 8, including at least one of an identifier at the Xn interface of the user equipment of the traffic offload initiation node (UE XnAP ID), a BAP address of the access IAB node, a TNL address, one or more F1-C identification information, one or more F1-U tunnel identification information, IP header information of the F1-C and / or each F1-U tunnel, or QoS information of each F1-U tunnel. (Appendix 10) If the traffic offload request for the F1-C and / or F1-U tunnel is accepted, the TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message may include: 10. The method of claim 9, further comprising at least one of a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of the traffic offload accepting node, identification information of the F1-C and / or F1-U tunnel, a newly allocated TNL address for a DU of an access IAB node, a BH RLC channel identifier on a link between a dual-connected IAB node and a second parent node configured for the F1-C and / or F1-U tunnel, a BAP address of a second parent node, a BAP routing identifier in a topology controlled by the second IAB-donor-CU, and a second BAP address of the IAB node. (Appendix 11) The method of claim 9, wherein if the traffic offload request for all F1-C and F1-U tunnels is rejected, the traffic offload request reject message includes the UE XnAP ID of the traffic offload initiation node. (Appendix 12) an IAB node is connected to a first parent node, the IAB node is connected to a second parent node, the first parent node being a node in the topology of the first IAB-donor-CU, and the second parent node being a node in the topology of the second IAB-donor-CU; The method described in Supplementary Note 1, wherein the first IAB-donor-CU is a master node (MN), and the contents of the traffic offload request and the contents of the response agreeing to the traffic offload or the response rejecting the traffic offload are included as information elements (IEs) in a message of a secondary base station node modification preparation (S-NG-RAN node Modification Preparation) procedure of an XnAP. (Appendix 13) an IAB node is connected to a first parent node, the IAB node is not connected to a second parent node, the first parent node is a node in the topology of the first IAB-donor-CU, and the second parent node is a node in the topology of the second IAB-donor-CU; The method described in Supplementary Note 1, in which the content of the traffic offload request and the content of the response agreeing to the traffic offload or the response rejecting the traffic offload are included as information elements (IEs) in a message of a secondary base station node addition preparation (S-NG-RAN node addition preparation) procedure of the XnAP. (Appendix 14) 14. The method of claim 13, wherein the traffic offload request is included in a Secondary Node Addition Request (S-NODE ADDITION REQUEST) message sent by the first IAB-donor-CU to the second IAB-donor-CU. (Appendix 15) 14. The method of claim 13, wherein the response agreeing to the traffic offload is included in an S-NODE ADDITION REQUEST ACKNOWLEDGE message sent by the second IAB-donor-CU to the first IAB-donor-CU. (Appendix 16) The second IAB-donor-CU receives or transmits a redundant path release request; The method of claim 1, further comprising the step of the second IAB-donor-CU sending or receiving a redundant path release request acceptance message. (Appendix 17) The method described in Supplementary Note 16, wherein the redundant path release request includes a UE XnAP ID of a traffic offload initiating node, a UE XnAP ID of a traffic offload accepting node, a TNL address associated with an F1-C for which the redundant path needs to be released, or user plane transport layer information (UP Transport Layer Information) of an F1-U tunnel for which the redundant path needs to be released. (Appendix 18) When the MN in the first IAB-donor-CU and the second IAB-donor-CU transmits a redundant path release request, The method according to claim 16, wherein the content of the redundant path release request and the content of the redundant path release request acceptance message are included as IEs in a secondary base station node modification preparation (S-NG-RAN node Modification Preparation) procedure. (Appendix 19) The method described in Supplementary Note 1, wherein when performing a secondary base station node release (S-NG-RAN node Release) procedure for an IAB node, all redundant paths related to the IAB node in the SN topology are released.

[0300] Dual-connected IAB node side method: (Appendix 1) A signal transmission / reception method applied to an IAB node, the IAB node being connected to a first parent node, the IAB node being already connected or to be connected to a second parent node, the first parent node being a node in a topology of a first IAB-donor-CU, and the second parent node being a node in a topology of a second IAB-donor-CU; The method comprises: receiving a first RRC reconfiguration message sent by the first IAB-donor-CU; sending an RRC reconfiguration complete message to the first IAB-donor-CU; The first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to the first IAB-donor-CU; The first RRC reconfiguration message includes at least one TNL address assigned to a DU of the IAB node, the TNL address being anchored to a second IAB-donor-DU in a topology of the second IAB-donor-CU; The method, wherein the RRCReconfigurationComplete message is used to indicate that the IAB node has received the first RRC reconfiguration message. (Appendix 2) receiving a second RRC Reconfiguration message sent by the second IAB-donor-CU, the second RRC Reconfiguration message including BAP configuration information (bap-Config), the BAP configuration information including a second BAP address configured for the IAB node; and the IAB node sending a reconfiguration complete (RRCReconfigurationComplete) message to the second IAB-donor-CU; The method of claim 1, wherein the reconfiguration complete (RRCReconfigurationComplete) message is used to indicate that the IAB node has received the second RRC Reconfiguration message. (Appendix 3) The method of claim 2, further comprising a step of the IAB node associating the second BAP address with a master cell group (MCG) / secondary cell group (SCG) or a master node (MN) / secondary node (SN). (Appendix 4) If the second RRCReconfiguration message having the second BAP address received by the IAB node is from an MCG or is received via a signaling radio bearer 1 (SRB), associate the second BAP address with an MCG or MN; The method described in Supplementary Note 3, wherein if the second RRC Reconfiguration message having the second BAP address received by the IAB node is from an SCG or received via SRB3, the second BAP address is associated with an SCG or SN. (Appendix 5) a BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a field for indicating a second BAP address configured for the IAB node; or 2. The method of claim 1, wherein a BAP address field in a BAP configuration information element (bap-Config IE) of the first RRC reconfiguration message includes a list, and each entry in the list is a BAP address and its associated information.

[0301] Descendant node side: (Appendix 1) A method for transmitting and receiving signals, applied to a descendant node of an IAB node, the IAB node being connected to a first parent node, the IAB node being already connected or to be connected to a second parent node, the first parent node being a node in a topology of a first IAB-donor-CU, and the second parent node being a node in a topology of a second IAB-donor-CU; The method comprises: receiving a first RRC reconfiguration message sent by the first IAB-donor-CU; sending an RRC reconfiguration complete message to the first IAB-donor-CU; The first RRC reconfiguration message is generated in response to a response agreeing to traffic offload sent by a second IAB-donor-CU to the first IAB-donor-CU; The first RRC reconfiguration message includes at least one TNL address assigned to a DU of the descendant node, and the TNL address is anchored to a second IAB-donor-DU in a topology of the second IAB-donor-CU; The method, wherein the RRCReconfigurationComplete message is used to indicate that the descendant node has received the first RRC reconfiguration message.

Claims

1. A signal transmission and reception apparatus, applied to a first access backhaul integrated node donor aggregation unit (IAB-donor-CU), the apparatus includes a first controller, the first controller comprising: Sending a traffic offload request to a second IAB-donor-CU; configured to receive a response agreeing to the traffic offload or a response rejecting the traffic offload sent by the second IAB-donor-CU; an IAB node is connected to a first parent node, said IAB node is connected or will be connected to a second parent node, said first parent node being a node in the topology of said first IAB-donor-CU, and said second parent node being a node in the topology of said second IAB-donor-CU; the traffic offload request is included in a TRAFFIC OFFLOAD REQUEST message, a response agreeing to the traffic offload is included in a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message, and a response rejecting the traffic offload is included in a TRAFFIC OFFLOAD REQUEST REJECT message.

2. The first controller includes: configured to transmit a first RRC reconfiguration message to the IAB node and / or a descendant IAB node of the IAB node in response to the response agreeing to the traffic offload; 2. The apparatus of claim 1, wherein the first RRC reconfiguration message includes at least one TNL address assigned to the IAB node and / or a descendant node of the IAB node, the TNL address being anchored to a second IAB-donor-DU in a topology of the second IAB-donor-CU.

3. The apparatus of claim 1 , wherein the traffic offload request comprises a request to establish a redundant path for an IAB node and / or a descendant node of the IAB node.

4. The first controller includes: The apparatus of claim 3 , further comprising: a first IAB-donor-CU configured to configure a BAP routing identifier mapping for the IAB node in response to the first IAB-donor-CU responding agreeing to the traffic offload.

5. the traffic offload agreeing response indicates at least partial acceptance of the traffic offload request; The apparatus of claim 1 , wherein at least partially accepting the traffic offload request means establishing redundant paths for F1-C or some F1-U tunnels associated with some TNLs.

6. The traffic offload request message: The apparatus of claim 1, further comprising at least one of an identifier of a user equipment of a traffic offload initiation node at an Xn interface (UE XnAP ID), a TNL address, one or more F1-C identification information, one or more F1-U tunnel identification information, and QoS information of each F1-U tunnel.

7. If the traffic offload request for the F1-C and / or F1-U tunnel is accepted, the TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message may include:

7. The apparatus of claim 6, further comprising at least one of a UE XnAP ID of the traffic offload initiating node, a UE XnAP ID of a traffic offload accepting node, identification information of the F1-C and / or F1-U tunnel, a newly allocated TNL address for an IAB node, a BH RLC channel identifier on a link between a dual-connected IAB node and a second parent node configured for the F1-C and / or F1-U tunnel, a BAP address of a second parent node, and a BAP routing identifier in a topology controlled by the second IAB-donor-CU.

8. The apparatus of claim 6, wherein if the traffic offload request for all F1-C and F1-U tunnels is rejected, the TRAFFIC OFFLOAD REQUEST REJECT message includes a UE XnAP ID of a traffic offload initiating node.

9. The first controller includes: Sending or receiving a redundant path release request for the first IAB-donor-CU; The apparatus of claim 1 , configured to receive or transmit a redundant path release request accept message for the first IAB-donor-CU.

10. 10. The apparatus of claim 9, wherein the redundant path release request includes a UE XnAP ID of a traffic offload initiating node, a UE XnAP ID of a traffic offload accepting node, a TNL address associated with an F1-C for which the redundant path needs to be released, or user plane transport layer information (UP Transport Layer Information) of an F1-U tunnel for which the redundant path needs to be released.

11. The apparatus of claim 1, further comprising: when performing a secondary base station node release (S-NG-RAN node Release) procedure for an IAB node, releasing all redundant paths associated with the IAB node in an SN topology.

12. A signal transmission / reception apparatus, applied to a second access backhaul integrated node donor aggregation unit (IAB-donor-CU), the apparatus includes a second controller, the second controller comprising: receiving a traffic offload request sent by a first IAB-donor-CU; configured to send a response to the first IAB-donor-CU agreeing to the traffic offload or a response to reject the traffic offload; an IAB node is connected to a first parent node, said IAB node is connected or will be connected to a second parent node, said first parent node being a node in the topology of said first IAB-donor-CU, and said second parent node being a node in the topology of said second IAB-donor-CU; the traffic offload request is included in a TRAFFIC OFFLOAD REQUEST message, a response agreeing to the traffic offload is included in a TRAFFIC OFFLOAD REQUEST ACKNOWLEDGE message, and a response rejecting the traffic offload is included in a TRAFFIC OFFLOAD REQUEST REJECT message.

13. 13. The apparatus of claim 12, wherein the traffic offload request comprises a request to establish a redundant path for an IAB node and / or a descendant node of the IAB node.

14. A signal transmission / reception device applied to an IAB node, the IAB node being connected to a first parent node, the IAB node being already connected or to be connected to a second parent node, the first parent node being a node in a topology of a first IAB-donor-CU, and the second parent node being a node in a topology of a second IAB-donor-CU; The apparatus includes a third controller, the third controller comprising: the IAB node receives a second RRC Reconfiguration message sent by the second IAB-donor-CU, the second RRC Reconfiguration message including BAP configuration information (bap-Config), the BAP configuration information including a second BAP address configured for the IAB node; The IAB node is configured to send an RRC Reconfiguration Complete message to the second IAB-donor-CU; The RRCReconfigurationComplete message is used to indicate that the IAB node has received the second RRC Reconfiguration message.

15. The third controller includes:

15. The apparatus of claim 14, wherein the IAB node is configured to associate the second BAP address with a master cell group (MCG) / secondary cell group (SCG) or a master node (MN) / secondary node (SN).

16. if the second RRCReconfiguration message received by the IAB node having the second BAP address is from an MCG or received via a signalling radio bearer (SRB), associate the second BAP address with an MCG or a MN; 16. The apparatus of claim 15, further comprising: if the second RRCReconfiguration message having the second BAP address received by the IAB node is from an SCG or received via an SRB3, associating the second BAP address with an SCG or an SN.

17. The first controller includes:

3. The apparatus of claim 2, configured to, when a new TNL address is assigned, add the new TNL address to an F1-C association between a DU of the IAB node and / or a descendant node of the IAB node and the first IAB-donor-CU.

18. The first controller includes:

4. The apparatus of claim 3, wherein the first IAB-donor-CU is configured to configure a BH RLC channel and a routing table of a BAP sublayer between the IAB node and a descendant node of the IAB node to support second path routing and BH RLC channel mapping.

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