Communication method and device

Abstract

The embodiments of the present application disclose a communication method and apparatus for improving stability and reliability of data transmission in an Integrated Access and Backhaul (IAB) network. A first node is served by a first Master Cell Group (MCG) and a first Secondary Cell Group (SCG), and a child node of the first node is a second node. The method is for the first SCG to transmit F1 interface user plane services, and includes the first node sending an RLF indication information to the second node when no Radio Link Failure (RLF) occurs in the first MCG and an RLF occurs in the first SCG.

Description

[Technical field]

[0001]

[0001] This application claims priority to Chinese Patent Application No. 202210014284.4, entitled "COMMUNICATION METHOD AND APPARATUS," filed with the State Intellectual Property Office of the People's Republic of China on January 6, 2022, the entire contents of which are incorporated herein by reference.

[0002]

[0002] This application relates to communications technology, and in particular to communications methods and devices. [Background technology]

[0003]

[0003] To support enhanced mobile broadband (eMBB) and ultra-reliable and low-latency communication (URLLC) service scenarios, the 5th generation (5G) new radio (NR) protocol standard uses higher frequency bands, including sub-6 gigahertz (GHz) frequency bands and millimeter wave frequency bands, to obtain more bandwidth resources. High frequency signals have poor propagation characteristics, short wavelengths, small signal coverage, and are severely attenuated by obstacles. This requires a large number of small base stations to be densely deployed. However, providing optical fiber backhaul to a large number of densely deployed small base stations requires high costs and is very difficult to build. Therefore, a cost-effective and convenient backhaul solution is required. Furthermore, when providing network coverage to some remote areas to meet wide-area coverage requirements, the deployment of optical fiber is difficult and costly. Therefore, it is necessary to design flexible and convenient access and backhaul solutions. Wireless transmission solutions are used for the access links and backhaul links in the Integrated Access and Backhaul (IAB) technology. This reduces the amount of optical fiber to be deployed. In this way, NR cells can be deployed flexibly and densely, and there is no need to deploy wired transmission networks proportionately densely. The IAB technology can support various deployment scenarios, including supporting outdoor small base station deployments, indoor small base station deployments, and even mobile relays, for example in buses and trains.

[0004]

[0004] The coverage of high-band signals is small. To ensure network coverage, IAB supports multi-hop networking and flexible scalability. Between a User Equipment (UE) served by an IAB node and an IAB donor, there is at least one transmission path formed by multiple links. Each transmission path may include a UE, one or more IAB nodes, an IAB donor distributed unit (IAB-donor-DU), and an IAB donor central unit (IAB-donor-CU). Each IAB node considers the neighboring node that provides access and backhaul services to the IAB node as a parent node. Accordingly, each IAB node can be considered as a child node of the parent node of that IAB node.

[0005]

[0005] In order to improve the reliability of service transmission, an IAB node may support dual connectivity (DC) to deal with possible exceptions of the backhaul link, such as link blockage and load fluctuation. Therefore, how to notify the radio link failure of an IAB node with dual connectivity, perform radio link recovery, and ensure stable data transmission between a UE and an IAB donor becomes an urgent technical problem to be solved. Summary of the Invention

[0006]

[0006] The present application provides a communication method and apparatus that improves the stability and reliability of data transmission in an IAB network and helps alleviate problems of data packet stacking, link congestion, and excessively long latency in IAB nodes.

[0007]

[0007] According to a first aspect, a first node is configured to transmit a first RLF indication to a second node, A Radio Link Failure (RLF) occurs in the backhaul link of one of the two cell groups that is intended to carry FI Interface User Plane (F1-U) services; or When an RLF occurs in a backhaul link of a cell group of the two cell groups that is intended to carry F1-U services, and link recovery is performed; or If an RLF occurs in a backhaul link of one of the two cell groups that is configured to carry F1 interface services based on a backhaul adaptation protocol (BAP) layer, or When an RLF occurs in a backhaul link of a cell group of two cell groups, the cell group being configured to carry an F1 interface service based on a BAP layer, and link recovery is performed, a first node is served by the two cell groups, and a child node of the first node is a second node.

[0008]

[0008] Transmitting the F1 interface service based on the BAP layer includes transmitting an F1-U service and / or an F1 interface control plane (F1-C) service based on the BAP layer. In a control plane-user plane (CP-UP) separation scenario in the DC scenario, transmitting the F1 interface service based on the BAP layer may include transmitting an F1-U service based on the BAP layer. The F1-C service may be transmitted based on the RRC layer (i.e., an F1-C service via RRC). In a non-CP-UP separation scenario in the DC scenario, transmitting the F1 interface service based on the BAP layer includes transmitting an F1-U service and an F1-C service based on the BAP layer.

[0009]

[0009] A first node with dual connectivity has two parent nodes, each of which provides a cell group to the first node. In this application, a backhaul link in a cell group is a connection channel established between a mobile terminal (MT) of the first node and a distributed unit (DU) of the parent node based on a cell group configured for some parent node of the first node, for backhaul transmission or forward transmission of data packets.

[0010]

[0010] Thus, the first node can trigger the transmission of the first RLF indication information by detecting that an RLF occurs in the backhaul link of the cell group for transmitting the F1-U service, or by detecting that an RLF occurs in the backhaul link of the cell group configured to transmit the F1 interface service based on the BAP, thereby improving the stability and reliability of data transmission in the IAB network. In some scenarios, it can reduce the problems of data packet stacking, link congestion, and excessively long delay of the second node caused by unnecessary RLF indication. For example, in the CP-UP separation scenario of the DC scenario, when the cell group for transmitting the F1 interface control plane (F1-C) service is the MCG and an RLF occurs, and the cell group for transmitting the F1-U service is the SCG and an RLF does not occur, the first node does not promptly transmit the first RLF indication information to the second node based on the triggering method of the first RLF indication information. In this way, the impact on the normal operation of the SCG for carrying F1-U services can be reduced. Furthermore, the second node can continue to route data to the first node. This helps to mitigate the problems of data packet stacking, link congestion, and excessively long latency of the second node.

[0011]

[0011] Furthermore, in some scenarios, the RLF indication can be sent in a timely manner, so that the second node can trigger to stop sending data packets to the first node, or the second node can trigger a rerouting operation of the data packets routed by the first node. This helps to alleviate the problems of data packet stacking, link congestion, and excessively long latency of the first node. For example, when the cell group for transmitting the F1-U service is an SCG and the RLF occurs only in the SCG, the first node sends the first RLF indication information to the second node according to the triggering method of the first RLF indication information, and the second node can trigger to stop sending data packets to the first node, or the second node can trigger a rerouting operation of the data packets routed by the first node. In this way, the problems of data packet stacking, link congestion, and excessively long latency at the first node can be mitigated.

[0012]

[0012] When an RLF is detected to occur in a backhaul link in a cell group configured to transmit an F1 interface service based on the BAP, transmission of a first RLF indication information is triggered. When an RLF is detected to occur in the backhaul links in all cell groups configured to transmit an F1 interface service based on the BAP, the first RLF indication information indicates that an RLF has occurred in a node-granularity link between the first node and the second node, i.e., an RLF has occurred in the entire backhaul link between the first node and the second node.

[0013]

[0013] According to a second aspect, an embodiment of the present application provides a communication method, wherein a first node is served by a first Master Cell Group (MCG) and a first Secondary Cell Group (SCG), and a child node of the first node is a second node, and the method may include: the first SCG is for transmitting F1 interface user plane services, and when RLF has not occurred in the first MCG and RLF has occurred in the first SCG, the first node sends first RLF indication information to the second node.

[0014]

[0014] In a possible design, when the first SCG is for carrying F1 interface user plane services, and RLF does not occur in the first MCG, and RLF occurs in the first SCG, the first node sending a first RLF indication information to the second node includes: The first SCG may be for carrying F1 interface user plane services, and may include the first node sending an RLF indication information to the second node when an RLF has occurred in the first MCG and an RLF has occurred in the first SCG, and link recovery is performed.

[0015]

[0015] In a possible design, the first SCG is for carrying F1 interface user plane services may include: the first SCG is for carrying F1 interface user plane services based on a backhaul adaptation protocol (BAP).

[0016]

[0016] In a possible design, the first MCG is only for carrying F1 interface control plane services, and the RLF indication information indicates that an RLF occurs on a node granular link between the first node and the second node, which means that the entire BH link between the first node and the second node is unavailable.

[0017] In a possible design, the RLF indication information may indicate that RLF is occurring on a node granular link between the first node and the second node by: The RLF indication information may include indicating that an RLF has occurred on a node granular link between the first node and the second node and that link recovery is to be performed.

[0018]

[0018] In a possible design, the first MCG is also for transmitting F1 interface user plane services, and the RLF indication information includes a first BAP address, a first routing identifier Routing ID, or a first path identifier Route ID.

[0019]

[0019] In a possible design, the first node determines that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first BAP address, where the first BAP address is the BAP address of the destination node; the first node determines that a route with a first route ID is unavailable on all routes through the first node to the destination node, and the RLF indication information includes the first route ID; or the first node determines that a route with a first routing ID is unavailable on all routes through the first node to the destination node, and the RLF indication information includes the first routing ID.

[0020]

[0020] According to a third aspect, an embodiment of the present application provides a communication method, wherein a first node is served by a first MCG and a first SCG, and a child node of the first node is a second node, and the method may include: the first MCG is for transmitting F1 interface user plane services, and when an RLF occurs in the first MCG and link recovery is performed, the first node sending RLF indication information to the second node.

[0021]

[0021] In a possible design, the first MCG being for transmitting F1 interface user plane services may include: the first MCG being for transmitting F1 interface user plane services based on a BAP.

[0022]

[0022] In a possible design, the first SCG is only for carrying F1 interface control plane services, and the RLF indication information indicates that RLF is occurring on a node granular link between the first node and the second node.

[0023]

[0023] In a possible design, the first SCG is also for transmitting F1 interface user plane services, no RLF occurs in the first SCG, and the first RLF indication information includes a first BAP address, a first routing identifier Routing ID, or a first path identifier Route ID.

[0024]

[0024] In a possible design, the first node determines that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first BAP address, where the first BAP address is the BAP address of the destination node; the first node determines that a route with a first route ID is unavailable on all routes through the first node to the destination node, and the RLF indication information includes the first route ID; or the first node determines that a route with a first routing ID is unavailable on all routes through the first node to the destination node, and the RLF indication information includes the first routing ID.

[0025] According to a fourth aspect, an embodiment of the present application provides a communication method, wherein a first node is served by a first MCG and a first SCG, and a child node of the first node is a second node, the method comprising the steps of:

[0026] a second node receiving a first RLF indication sent by the first node, the first RLF indication including a first backhaul adaptation protocol (BAP) layer address, or a first routing identifier (Routing ID), or a first path identifier (Path ID); The method may include a step in which the second node skips sending the first data packet to the first node based on the first RLF indication information, and a routing identifier carried in the first data packet is a first routing ID, a route identifier in the routing identifier carried in the first data packet is the first route ID, or a BAP address in the routing identifier carried in the first data packet is the first BAP address.

[0026]

[0027] According to a fifth aspect, the present application provides a communication device including at least one processor and an interface, the interface being configured to input and / or output signals. For example, the interface is configured to receive signals from a communication device other than the communication device and send the signals to the processor and / or to transmit signals from the processor to a communication device other than the communication device. The processor is configured to enable the communication device to perform the aforementioned method. For example, the processor implements any method in the first, second or third aspect by using logic circuits and / or executing program instructions.

[0027]

[0028] Optionally, the apparatus may be a chip or integrated circuit within a node in the first aspect, the second aspect or the third aspect.

[0028]

[0029] Optionally, the communication device may further include at least one memory, the memory storing program instructions. The processor is coupled to the at least one memory and configured to execute the program to realize the method design described above.

[0029]

[0030] According to a sixth aspect, the present application provides a communication device. The device has components, modules, units or means for implementing any one of the methods of the first aspect, the second aspect or the third aspect, and any design thereof. The device can be implemented using hardware, software, firmware or any combination thereof. For example, the device may be implemented by hardware executing corresponding software. The hardware or software includes one or more corresponding units (modules) configured to implement the aforementioned method design, including, for example, a transceiver unit and a processing unit.

[0030]

[0031] According to a seventh aspect, the present application provides a computer readable storage medium storing program instructions which, when executed by a processor, perform any of the methods of the first aspect, the second aspect or the third aspect, and any design thereof.

[0031]

[0032] According to an eighth aspect, the present application provides a computer program product comprising program instructions which, when executed by a processor, perform any method of the first aspect, the second aspect or any third aspect, and any design thereof.

[0032]

[0033] According to a ninth aspect, the present application further provides a chip, the chip configured to perform any of the methods of the first aspect, the second aspect or the third aspect, and any design thereof.

[0033]

[0034] It should be understood that the technical solutions of the fourth to eighth aspects of the present application are consistent with the technical solutions of the first to third aspects of the present application. The beneficial effects achieved by these aspects and corresponding possible implementations are similar, and the details will not be described again. [Brief description of the drawings]

[0034]

[0035] The solutions provided in the present application are described in detail below with reference to the accompanying drawings. Features or contents shown with dashed lines in the drawings may be understood as optional processes or optional structures in the embodiments of the present application. [Figure 1]

[0036] FIG. 1 is a diagram of an IAB network communication system. [Diagram 2]

[0037] Figure 2 shows the control plane protocol stack of the IAB network. [Diagram 3]

[0038] Figure 3 is a diagram of the IAB network user plane protocol stack. [Figure 4]

[0039] FIG. 4 is a diagram of a communication scenario. [Diagram 5]

[0040] FIG. 5 is a diagram of a dual connectivity communication scenario. [Figure 6]

[0041] FIG. 6 is a diagram of a communication architecture. [Figure 7]

[0042] FIG. 7 is a diagram of a communication scenario. [Figure 8]

[0043] FIG. 8 is a diagram of the cross-donor base station handover process. [Figure 9]

[0044] FIG. 9 is a diagram of a method for indicating a radio link failure. [Figure 10]

[0045] FIG. 10 is a diagram of the CP-UP separation scenario in the EN-DC scenario. [Figure 11]

[0046] FIG. 11 is a diagram of the CP-UP separation scenario in the NR-DC scenario. [Figure 12]

[0047] FIG. 12 is a diagram of an IAB network communication system in the EN-DC form of networking. [Figure 13]

[0048] FIG. 13 is a diagram of an IAB network communication system in the NR-DC form of networking. [Figure 14]

[0049] FIG. 14 is a flow chart of a radio link failure indication method. [Figure 15]

[0050] FIG. 15 is a flow chart of a radio link failure indication method. [Figure 16]

[0051] FIG. 16 is a flow chart of a radio link failure indication method. [Figure 17A]

[0052] FIG. 17A is a diagram of an RLF scenario. [Figure 17B]

[0053] FIG. 17B is a diagram of an RLF scenario. [Figure 18]

[0054] FIG. 18 is a flow chart of a radio link failure indication method. [Figure 19A]

[0055] FIG. 19A is a diagram of an RLF scenario. [Figure 19B]

[0056] FIG. 19B is a diagram of an RLF scenario. [Figure 20]

[0057] FIG. 20 is a flow chart of a radio link failure indication method. [Figure 21]

[0058] FIG. 21 is a block diagram of a communication device 2100. [Figure 22]

[0059] FIG. 22 is a block diagram of a communication device 2200. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035]

[0060] FIG. 1 is a diagram of an IAB network communication system according to the present application. The communication system includes a terminal, an IAB node, and a donor base station. In the present application, the term "IAB network" is merely an example and may be replaced with a "wireless backhaul network" or a "relay network". The term "IAB node" is also merely an example and may be replaced with a "wireless backhaul device" or a "relay node".

[0036]

[0061] A donor base station may function as a donor node for an IAB node. In this application, a donor base station may include, but is not limited to, a next generation base station (gNB), an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NB), a base station controller (BSC), a base transceiver station (BTS), a home evolved NodeB or home NodeB, a transmission and reception point or transmission point, a road side unit (RSU) with base station functionality, a baseband unit (BBU), a remote radio unit (RRU), an active antenna unit (AAU), one or a group of antenna panels, a node with base station functionality in a subsequent evolved system, or the like. The donor base station may be an entity, and may further include a central unit (CU) entity and at least one distributed unit (DU) entity. The interface between the CU and the DU may be referred to as an F1 interface. The two ends of the F1 interface are the CU and the DU. The peer end of the F1 interface of the CU is the DU, and the peer end of the F1 interface of the DU is the CU. The F1 interface may further include a control plane F1 interface (F1-C) and a user plane F1 interface (F1-U). In this application, the CU of the donor base station may be referred to as a donor CU for short, and the DU of the donor base station may be referred to as a donor DU for short.

[0037]

[0062] In this application, the terminal may also be referred to as user equipment (UE), mobile station, terminal device, etc. The terminal may be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), internet of things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable device, smart transportation, smart city, etc. The terminal may be a mobile phone, a tablet computer, a computer with wireless transceiver capability, a wearable device, a vehicle, an unmanned aerial vehicle, a helicopter, an airplane, a ship, a robot, a robot arm, a smart home device, etc. The terminal may include, but is not limited to, a user equipment (UE), a mobile station, a mobile device, a terminal device, a user agent, a mobile phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a portable device with wireless communication capability, a computing device, or other processing device connected to a wireless modem, an in-vehicle device, a wearable device (such as a smart watch, a smart band, or smart glasses), a smart furniture or appliance, a vehicle device in a vehicle-to-everything (V2X), a terminal device with relay capability, a customer premises equipment (CPE), an IAB node (specifically an IAB node functioning as a MT or terminal of an IAB node), etc. The specific name and implementation form of the terminal are not limited in this application.

[0038]

[0063] In the present application, an IAB node may include at least one mobile terminal (MT) and at least one distributed unit (DU). An IAB node may be an entity. For example, an IAB node includes at least one MT function and at least one DU function. An IAB node may alternatively include multiple entities. For example, an IAB node includes at least one MT entity and at least one DU entity. The MT entity and the DU entity may communicate with each other, for example, by using a network cable. If an IAB node is oriented toward a parent node of the IAB node (where the parent node may be a donor base station or another IAB node), the IAB node may, for example, play the role of a terminal used in various scenarios in which the aforementioned terminal is used, i.e., a terminal of the IAB node. In this case, the MT function or MT entity provides the functionality of a terminal of the IAB node. If an IAB node is directed to a child node of the IAB node (where the child node may be another IAB node or a terminal), the IAB node may act as a network device, i.e., a network device of the IAB node. In this case, the DU function or DU entity provides the IAB node with the functionality of a network device. In this application, the MT of the IAB node may be referred to as IAB-MT for short, and the DU of the IAB node may be referred to as IAB-DU for short. An IAB node may be connected to a donor base station or may be connected to a donor base station via another IAB node.

[0039]

[0064] The IAB network supports multi-hop networking and multi-connection networking to ensure the reliability of service transmission. An IAB node regards an IAB node providing a backhaul service to the IAB node as a parent node. Accordingly, an IAB node may regard a child node of the parent node of the IAB node. A terminal may alternatively regard an IAB node accessed by the terminal as a parent node. Accordingly, an IAB node may alternatively regard a terminal accessed by the IAB node as a child node. An IAB node may regard a donor base station accessed by the IAB node as a parent node. Accordingly, a donor base station may alternatively regard an IAB node accessed by the donor base station as a child node.

[0040] As shown in FIG. 1, the parent node of IAB node 1 includes a donor base station. IAB node 1 is also the parent node of IAB node 2 or IAB node 3. The parent node of terminal 1 includes IAB node 4. The child node of IAB node 4 includes terminal 1 or terminal 2. An IAB node directly accessed by a terminal may be called an access IAB node. IAB node 4 in FIG. 1 is the access IAB node of terminal 1 and terminal 2. IAB node 5 is the access IAB node of terminal 2.

[0041] A node on an upstream transmission path from an IAB node to a donor base station may be referred to as an upstream node of the IAB node. An upstream node may include a parent node, a parent node of a parent node (also called a grandparent node), etc. For example, IAB node 1 and IAB node 2 in FIG. 1 may be referred to as upstream nodes of IAB node 5.

[0042] A node on a downstream transmission path from an IAB node to a terminal may be referred to as a downstream node or a descendant node of the IAB node. A downstream node or a descendant node may include a child node, a child node of a child node (also called a grandchild node), a terminal, etc. For example, terminal 1, terminal 2, IAB node 2, IAB node 3, IAB node 4, or IAB node 5 in FIG. 1 may be referred to as a downstream node or a descendant node of IAB node 1. As another example, IAB node 4 and IAB node 5 in FIG. 1 may be referred to as a downstream node or a descendant node of IAB node 2. Terminal 1 in FIG. 1 may be referred to as a downstream node or a descendant node of IAB node 4.

[0043] Each IAB node needs to maintain a backhaul link (BL) towards its parent node. If the child node of the IAB node is a terminal, the IAB node further needs to maintain an access link (AL) between the IAB node and the terminal. As shown in Figure 1, the link between IAB node 4 and terminal 1 or terminal 2 includes an AL. The link between IAB node 4 and IAB node 2 or IAB node 3 includes a BL.

[0044]

[0065] An upstream data packet transmitted by the terminal to the donor base station may be transmitted to the donor base station via one or more IAB nodes. Specifically, the target node of the upstream data between the terminal and the donor base station may be the donor base station. A downstream data packet transmitted by the donor base station to the terminal may be transmitted to the access IAB node of the terminal via one or more IAB nodes, and then the downstream data packet is transmitted to the terminal by the access IAB node. Specifically, the target node of the downstream data between the terminal and the donor base station is the access IAB node. For example, there are two available paths for data transmission between terminal 1 and the donor base station: Route 1: Terminal 1 ←→ IAB node 4 ←→ IAB node 3 ←→ IAB node 1 ←→ donor base station, and Route 2: Terminal 1 ←→ IAB node 4 ←→ IAB node 2 ←→ IAB node 1 ←→ Donor base station For data transmission between terminal 21 and the donor base station, there are three possible paths: Route 1: Terminal 2 ←→ IAB node 4 ←→ IAB node 3 ←→ IAB node 1 ←→ donor base station, Route 2: Terminal 2 ←→ IAB node 4 ←→ IAB node 2 ←→ IAB node 1 ←→ donor base station, and Route 3: Terminal 2 ←→ IAB node 5 ←→ IAB node 2 ←→ IAB node 1 ←→ Donor base station It can be understood that in an IAB network, one transmission path between a terminal and a donor base station may include one or more IAB nodes. Each IAB node needs to maintain a wireless backhaul link (BL) toward a parent node. If the child node of an IAB node is a terminal, there is a wireless access link (AL) between the IAB node and the terminal. As shown in Figure 1, in a path 1 between a terminal 1 and a donor base station, the terminal 1 accesses an IAB node 4 via an AL, the IAB node 4 is connected to an IAB node 3 via a BL, the IAB node 3 is connected to an IAB node 1 via a BL, and the IAB node 1 is connected to a donor base station via a BL.

[0045]

[0066] 2 and 3 are diagrams of a control plane protocol stack and a user plane protocol stack of an IAB network according to an embodiment of the present application, respectively. The donor base station in FIG. 2 and FIG. 3 may include a donor CU function and a donor DU function (in this case, the donor base station is one entity), or may include a donor CU entity and a donor DU entity function (in this case, the donor base station is divided into two entities). As shown in FIG. 2 or FIG. 3, the peer protocol layer between the donor DU and the donor CU includes an IP layer, a layer 2 (layer 2, L2), and a layer 1 (layer 1, L1). L1 and L2 may be referred to as protocol stack layers in a wired transmission (e.g., optical fiber transmission) network. For example, L1 may be a physical layer, and L2 may be a data link layer. Backhaul links (BL) are established between IAB node 4 and IAB node 3, between IAB node 3 and IAB node 1, and between IAB node 1 and the donor DU. The peer protocol stacks at both ends of the BL may include a backhaul adaptation protocol (BAP) layer, a radio link control (RLC) layer, a media access control (MAC) layer, and a physical (PHY) layer.

[0046]

[0067] As shown in FIG. 2, there is an interface between the terminal and the donor base station, and sometimes the interface is also an air interface. For example, the air interface may be called a Uu interface. One end of the Uu interface is located in the terminal, and the other end is located in the donor base station. The peer control plane protocol stacks at both ends of the Uu interface include a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, an RLC layer, a MAC layer, and a PHY layer. The protocol layers included in the Uu interface control plane protocol stack may also be called a control plane access stratum (AS). When the donor base station includes a donor CU entity and a donor DU entity, the control plane protocol stacks of the Uu interface at the donor base station side may be located in the donor DU and donor CU separately. For example, the PHY layer, the MAC layer, and the RLC layer are located in the donor DU, and the RRC layer and the PDCP layer are located in the donor CU.

[0047]

[0068] Between the DU of the IAB node (i.e., IAB node 4 in FIG. 2) accessed by the terminal and the donor base station, there is an interface, for example, called an F1 interface. One end of the F1 interface is located at the IAB node 4, and the other end is located at the donor base station. The peer end of the F1 interface of the donor base station (which may be, for example, a donor CU) is the IAB node (specifically, may be the DU of the IAB node), and the peer end of the F1 interface of the IAB node (which may be, specifically, may be the DU of the IAB node) is the donor base station (specifically, may be the donor CU). The peer control plane protocol stacks at both ends of the F1 interface include an F1 application protocol (F1AP) layer, a stream control transmission protocol (SCTP) layer, and an IP layer. The donor base station may include a donor CU entity and a donor DU entity. The control plane protocol stack of the F1 interface at the end of the donor base station may be located in the donor CU. For example, the donor CU includes an F1AP layer, an SCTP layer, and an IP layer. Alternatively, the control plane protocol stack of the F1 interface on the donor base station side may be separately arranged in the donor CU and the donor DU. For example, the donor CU includes an F1AP layer and an SCTP layer, and the donor DU includes an IP layer.

[0048] As shown in FIG. 3, the peer user plane protocol stack at both ends of the Uu interface between the terminal and the donor base station includes a service data adaptation protocol (SDAP) layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. The protocol layers included in the user plane protocol stack of the Uu interface may be referred to as a user plane access stratum (AS). When the donor base station includes a donor CU entity and a donor DU entity, the user plane protocol stack of the Uu interface at the donor base station side may be separately located in the donor DU and the donor CU. For example, the PHY layer, the MAC layer, and the RLC layer are located in the donor DU, and the SDAP layer and the PDCP layer are located in the donor CU.

[0049]

[0069] The peer user plane protocol layers at both ends of the F1 interface between the DU of the IAB node 4 and the donor base station include a general packet radio service tunnelling protocol for the user plane (GTP-U) layer, a user datagram protocol (UDP) layer, and an IP layer. The donor base station may include a donor CU entity and a donor DU entity. The user plane protocol stack of the F1 interface on the donor base station side may be located in the donor CU. For example, the donor CU includes a GTP-U layer, a UDP layer, and an IP layer. The user plane protocol stack of the F1 interface on the donor base station side may alternatively be located separately in the donor CU and the donor DU. For example, the donor CU includes a GTP-U layer and a UDP layer, and the donor DU includes an IP layer.

[0050]

[0070] In the control plane, the terminal's RRC message is encapsulated in an F1AP message by the access IAB node for transmission. Specifically, in the upstream direction, the terminal encapsulates the RRC message into a PDCP protocol data unit (PDU) and sends the PDCP protocol data unit to the DU of the IAB node after sequential processing is performed in the RLC layer, MAC layer, and PHY layer.

[0051] The DU of IAB node 4 obtains the PDCP PDU after sequential processing is performed at the PHY layer, MAC layer, and RLC layer, encapsulates it into an F1AP message, and obtains an IP packet after sequential processing is performed at the SCTP layer and IP layer. The DU of IAB node 4 transmits the IP packet to the MT of IAB node 4 via the internal interface. The MT of IAB node 4 transmits the IP packet to the DU of IAB node 3 after sequential processing is performed at the BAP layer, RLC layer, MAC layer, and PHY layer.

[0052] The DU of IAB node 3 obtains the IP packet after sequential processing is performed in the PHY layer, MAC layer, RLC layer, and BAP layer. The DU of IAB node 3 sends the IP packet to the MT of IAB node 3 via the internal interface, and then the MT of IAB node 3 sends the IP packet to the DU of IAB node 1 by using the same operation as the MT of IAB node 4.

[0053] Then, the DU of IAB node 1 sends the IP packet to the MT of IAB node 1 by using the same operation as the DU of IAB node 3. Similarly, the MT of IAB node 1 sends the IP packet to the donor DU.

[0054] After the donor DU obtains the IP packet through analysis, it sends the IP packet to the donor CU. The donor CU performs sequential processing on the IP packet at the SCTP layer, F1AP layer, and PDCP layer, and then obtains the RRC message of the terminal. The operation in the downstream direction is similar. The details will not be described again here.

[0055]

[0071] In the user plane, the terminal's data packets are encapsulated in PDCP PDUs and sent to the access IAB node after sequential processing in the RLC layer, MAC layer, and PHY layer. The access IAB node encapsulates the received PDCP PDUs in a GTP-U tunnel between the access IAB node and the donor CU for transmission. The GTP-U tunnel is established in the F1-U interface. For the specific process of forwarding the terminal's data packets, please refer to the aforementioned process of forwarding RRC messages in the control plane.

[0056]

[0072] Also, in Figures 2 and 3, when a terminal accesses a donor DU, the interface between the donor DU and the donor CU may also include an F1 interface. The peer control plane protocol stacks at both ends of the F1 interface include an F1AP layer, an SCTP layer, and an IP layer. The peer user plane protocol stacks at both ends of the F1 interface include a GTP-U layer, a UDP layer, and an IP layer. When a terminal accesses IAB node 1 or IAB node 3, an F1 interface may also be included between IAB node 1 or IAB node 3 and a donor base station. For a description of the F1 interface, please refer to the description of the F1 interface between the DU of IAB node 4 and a donor base station.

[0057]

[0073] When "terminal" refers to an MT function or MT entity of an IAB node, or an IAB node acting as a terminal, the protocol stack of the terminal shown in Figure 2 or Figure 3 is the protocol stack of the MT function or MT entity of the IAB node, or the protocol stack of the IAB node when it acts as a terminal.

[0058]

[0074] When accessing the IAB network, the IAB node can function as a terminal. In this case, the MT of the IAB node has a terminal protocol stack. There is an air interface (Uu interface) protocol stack between the IAB node and the donor base station. The terminal protocol stack in Figures 2 and 3 includes an RRC layer or an SDAP layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. In the control plane, the RRC message of the IAB node is encapsulated in an F1AP message by the parent node of the IAB node for transmission. In the user plane, the data packet of the IAB node is encapsulated in a PDCP protocol data unit (PDU) and sent to the parent node of the IAB node. The parent node of the IAB node encapsulates the received PDCP PDU in a GTP-U tunnel of the F1 interface between the parent node of the IAB node and the donor CU for transmission. Also, after the IAB node accesses the IAB network, the IAB node may still function as a common terminal. For example, the IAB node may transmit data packets of the IAB node, such as data packets of operations, administration and maintenance (OAM) network elements and measurement reports, to the donor base station.

[0059]

[0075] It should be noted that one IAB node may have one or more roles in the IAB network. For example, the IAB node may function as a terminal, or as an access IAB node (e.g., the protocol stack of IAB node 4 in Fig. 2 and Fig. 3) or an intermediate IAB node (e.g., the protocol stack of IAB node 1 or IAB node 3 in Fig. 2 and Fig. 3). For different roles, the IAB node may use different protocol stacks corresponding to the roles. When the IAB node has multiple roles in the IAB network, the IAB node may have multiple protocol stacks at the same time. The protocol stacks may share some of the same protocol layers, for example, the same RLC layer, the same MAC layer, and the same PHY layer.

[0060]

[0076] FIG. 4 is a diagram of a communication scenario. As shown in FIG. 4, a donor base station and an IAB node are included. The donor base station may include a donor CU and at least one donor DU. The communication interface between the donor base station and the IAB node may include an air interface (Uu interface) and an F1 interface. For example, there is an air interface (Uu interface) between the MT of the IAB node and the donor base station, and there is an F1 interface between the DU of the IAB node and the donor base station.

[0061]

[0077] The IP addresses of the IAB nodes are assigned to the IAB nodes by the donor DU or a network management device. The IP addresses of the donor CUs may also be assigned by a network management device. In this application, a network management device may include an operations, administration and maintenance (OAM) network element, an element management system (EMS), a network management system (NMS), etc.

[0062]

[0078] FIG. 5 is a diagram of a dual connection communication scenario. As shown in FIG. 5, a master base station, a secondary base station, and an IAB node are included. The donor base station of the IAB node is the secondary base station. The communication interface between the master base station and the IAB node includes an air interface (Uu interface). The communication interface between the secondary base station and the IAB node includes a Uu interface and an F1 interface.

[0063]

[0079] FIG. 6 is a diagram of a communication architecture. As shown in FIG. 6, donor base station 1 includes donor CU1 and donor DU1. Donor base station 2 includes donor CU2 and donor DU2. There is a communication interface between the IAB node and donor base station 1 or donor base station 2. For example, the communication interface between the IAB node and donor base station 1 or donor base station 2 may include a Uu interface and / or an F1 interface. There is also a communication interface between donor base station 1 and donor base station 2. Donor CU1 and donor CU2 may communicate with each other, for example, via an X2 or Xn interface. Donor CU1 and donor DU2, and donor CU2 and donor DU1 may also communicate with each other, for example, by using an IP network. It can be understood that the communication architecture shown in FIG. 6 may further include downstream or descendant nodes of the IAB node. An upstream node of the IAB node may further be included between the IAB node and the donor base station.

[0064]

[0080] FIG. 7 is a diagram of possible communication scenarios. As shown in FIG. 7, the IAB node includes an MT and DU portion (in this case, the IAB node is split into two entities), or an MT and DU function (in this case, the IAB node is one entity). The donor base station includes a donor CU entity and a donor DU entity (in this case, the donor base station is split into two entities), or a donor CU and a donor DU function (in this case, the donor base station is still one whole). An upstream node IAB node 2 (i.e., the parent node of IAB node 3) is further present between IAB node 3 and the donor base station. In FIG. 7, the thick curves indicate possible paths of communication on the F1 interface between the IAB node and the donor base station 1 or donor base station 2 in each scenario. It can be understood that in FIG. 7, another upstream node of IAB node 3 may be further included between IAB node 3 and IAB node 2, or between IAB node 3 and IAB node 1. In FIG. 7, another downstream node or descendant node of IAB node 3 may be further included. In FIG. 7, IAB node 1 may not be present. Specifically, IAB node 3 may be directly connected to donor base station 1. Alternatively, IAB node 2 may not be present. Specifically, IAB node 3 may be directly connected to donor base station 2. Several communication scenarios shown in FIG. 7 are described below.

[0065]

[0081] Communications Scenario A: 7 is the donor base station 1 (specifically, the donor CU is the donor CU1 and the donor DU is the donor DU1), there are a Uu interface and an F1 interface between the IAB node 3 and the donor base station 1. Communication in the F1 interface between the IAB node 3 and the donor base station 1 needs to go through the donor DU1.

[0066]

[0082] 7 is the donor base station 2 (the donor CU is the donor CU2 and the donor DU is the donor DU2), there are a Uu interface and an F1 interface between the IAB node 3 and the donor base station 2. Communication on the F1 interface between the IAB node 3 and the donor base station 2 needs to go through the donor DU2.

[0067]

[0083] Communication Scenario B: A Uu interface exists between the IAB node 3 and the donor base station 2 (including the donor CU2 and the donor DU2), and an F1 interface exists between the IAB node 3 and the donor base station 1. Communication on the F1 interface between the IAB node 3 and the donor base station 1 needs to go through the donor DU2.

[0068]

[0084] Communications Scenario C: A Uu interface exists between the IAB node 3 and the donor base station 1 (including donor CU1 and donor DU1), and an F1 interface exists between the IAB node 3 and the donor base station 2. In communication scenario C, an F1 interface may exist between the IAB node 3 and the donor base station 1, or may not exist (it can also be said that an F1 interface is not established between the IAB node 3 and the donor base station 1). Communication in the F1 interface between the IAB node and the donor base station 2 needs to go through the donor DU1.

[0069]

[0085] Communication Scenario D (also called dual connectivity scenario): A Uu interface exists between the IAB node 3 and the donor base station 1 (including donor CU1 and donor DU1), and a Uu interface exists between the IAB node and the donor base station 2. An F1 interface exists between the IAB node 3 and the donor base station 1. Communication in the F1 interface between the IAB node 3 and the donor base station 1 may go through donor DU1 or donor DU2. In other words, the donor base station 1 may choose to perform communication in the F1 interface with the IAB node 3 via donor DU1 and / or donor DU.

[0070]

[0086] The communication scenarios A, B, C, and D of the IAB node 3 may be converted to each other. For example, in the process of performing cross-donor base station handover in the IAB node 3, a switch from communication scenario A to communication scenario B or a switch from communication scenario A to communication scenario C may be included. In this case, the donor base station 1 may be called a source donor base station (S-donor) (S-donor), and the donor base station 2 may be called a target donor base station (T-donor) (T-donor). The S-donor may further include an S-donor CU1 and an S-donor DU1. The T-donor may further include a T-donor CU2 and a T-donor DU2. The process of performing cross-donor base station handover in the IAB node may be as shown in FIG. 8.

[0071]

[0087] FIG. 8 is a diagram of a cross-donor base station handover process. Before performing a cross-donor base station handover, the IAB node 3 may be in an initial stage. For a description of the initial stage, refer to the above description of communication scenario A.

[0072]

[0088] A possible cross-donor base station handover process includes the following: after the IAB node 3 receives a message from the donor base station 1, which indicates to the IAB node 3 that it is to be handed over from the donor base station 1 to the donor base station 2, the MT of the IAB node 3 is first handed over to the donor base station 2 (i.e., the air interface is handed over from the donor base station 1 to the donor base station 2), and the DU of the IAB node 3 still maintains the F1 interface between the IAB node 3 and the donor base station 1 (i.e., the F1 interface is not handed over). In this case, the IAB node is in the intermediate stage 1. For the communication between the IAB node 3 and the donor base station 1 or the donor base station 2 in the intermediate stage 1, please refer to the above description of the communication scenario B. Optionally, the IAB node 3 in the intermediate stage 1 can continue to hand over the F1 interface to the donor base station 2 (specifically, disconnect the F1 interface between the IAB node 3 and the donor base station 1, and establish the F1 interface between the IAB node 3 and the donor base station 2). In this case, the IAB node enters the final stage.

[0073]

[0089] Another possible cross-donor base station handover process includes: the IAB node 3 establishes an F1 interface with the donor base station 2 based on the received indication information, and the MT of the IAB node 3 still maintains the Uu interface between the IAB node 3 and the donor base station 1 (i.e., the Uu interface is not handed over). In this case, the IAB node is in the intermediate stage 2. The indication information may be from the donor base station 1 and instructs the IAB node 3 (specifically, may be the DU of the IAB node 3) to establish an F1 interface with the donor base station 2. For example, the indication information carries the IP address of the donor CU2. For the communication between the IAB node 3 and the donor base station 1 or the donor base station 2 in the intermediate stage 2, please refer to the above description of the communication scenario C. Optionally, after the IAB node 3 receives a message from the donor base station 1 indicating that it is to be handed over from the donor base station 1 to the donor base station 2, the IAB node 3 in the intermediate stage 2 may continue to hand over the Uu interface to the donor base station 2 (specifically, disconnect the Uu interface between the MT of the IAB node 3 and the donor base station 1, and establish the Uu interface between the MT of the IAB node 3 and the donor base station 1). In the communication scenario C or the intermediate stage 2, if an F1 interface exists between the IAB node 3 and the donor base station 1, in this case, the F1 interface between the IAB node 3 and the donor base station 1 may be disconnected. In this case, the IAB node enters the final stage.

[0074]

[0090] In the present application, establishing an interface may include establishing a connection and / or a bearer in the interface. For example, establishing a Uu interface may include at least one of establishing an RRC connection, establishing an SRB, and establishing a DRB. Establishing an F1 interface may include establishing an F1 connection.

[0075] Disconnecting the interface may include disconnecting a connection and / or a bearer in the interface. For example, disconnecting the Uu interface may include at least one of disconnecting an RRC connection, disconnecting an SRB, and disconnecting a DRB. Disconnecting the F1 interface may include disconnecting an F1 connection.

[0076]

[0091] As another example, the IAB node 3 may further switch from the communication scenario A or the communication scenario B to a dual connectivity communication scenario (communication scenario D). In this case, the donor base station 1 may be referred to as a master donor base station (M-donor), and the donor base station 2 may be referred to as a secondary donor base station (S-donor). The M-donor may further include an M-donor CU1 and an M-donor DU1. The S-donor may further include an S-donor CU2 and an S-donor DU2.

[0077]

[0092] To ensure stable data transmission between the UE and the IAB-donor, a radio link recovery mechanism is introduced. Specifically, after a Radio Link Failure (RLF) occurs between two IAB nodes, an attempt may be made to recover the radio link between the two IAB nodes. If an IAB node finds that an RLF occurs on a link between the IAB node and the parent node of the IAB node and the RLF recovery fails (e.g., RRC re-establishment fails), the IAB node sends RLF indication information to the child node of the IAB node, so that the child node of the IAB node triggers a link recovery procedure. For example, as shown in Figure 9, if an RLF occurs on a link between the IAB node and the parent node of the IAB node and the RLF recovery fails, the IAB node sends RLF indication information to the child node of the IAB node.

[0078]

[0093] However, in case of an IAB node with dual connectivity, the IAB node accesses two parent nodes in a dual connectivity manner. One of the two parent nodes acts as the Master Node (MN) of the IAB node and the other parent node acts as the Secondary Node (SN) of the IAB node. The Cell Group (CG) configured on the MN side is the Master Cell Group (MCG) and the Cell Group (SCG) configured on the SN side is the Secondary Cell Group. In other words, the IAB node is served by the MCG and the SCG.

[0079]

[0094] The condition for triggering an IAB node having a dual connection to send RLF indication information to a child node of the IAB node is that the IAB node initiates an RRC re-establishment, where the cause of the RRC re-establishment is: RLF occurs on the backhaul links (BLs) in two cell groups (CGs) of an IAB node, or RLF occurs on the backhaul link in the master cell group and master cell group fast recovery is not performed (no MCG fast recovery).

[0080] Such RLF indication scheme cannot guarantee stable data transmission. In particular, problems such as data packet stacking, link congestion, and excessively long latency may occur in some scenarios. These scenarios may include, but are not limited to, CP-UP separation scenarios in DC scenarios of IAB nodes. CP-UP separation means that the F1-U (F1 interface user plane) service and the F1-C (F1 interface control plane) service of an IAB node with dual connectivity do not reach the IAB donor via the same route.

[0081]

[0095] The IAB-MT encapsulates F1 interface user plane (F1-U) services in BAP layer data packets (e.g., BAP PDUs), and then forwards the packets to the IAB donor over the backhaul link (via at least one intermediate IAB node) based on the BAP layer routing and RLC channel mapping protocol of the backhaul link. This transmission mode may be called "F1 over BAP". "F1 over BAP" is also applicable to F1-C services in the general DC scenario without CP-UP separation.

[0082]

[0096] F1 interface control plane (F1-C) services are encapsulated by the IAB-MT in IAB-MT RRC messages, reach the MN or SN via the Uu interface of the non-F1 terminating node, and then reach the IAB donor via the inter-base station Xn interface or X2 interface. This transmission mode may be called "F1 over RRC". "F1 over RRC" applies to F1-C services.

[0083]

[0097] A non-F1 terminating node is a node that does not have an F1 interface with an IAB node in dual connection mode. For an IAB node in dual connection mode, it can be understood that if the IAB node transmits the F1-C service of the IAB node to an eNB or gNB connected to the IAB node via an LTE Uu interface or an NR Uu interface (instead of an F1 interface) by using the MT part of the IAB node, the eNB or gNB may be called a non-F1 terminating node. For example, in EN-DC networking, the non-F1 terminating node may be an MeNB. In NR-DC networking, the non-F1 terminating node may be an MgNB or an SgNB. The F1 terminating node is an IAB donor node. Specifically, the F1-U service and / or the F1-C service (both / either) are transmitted between the IAB node and the donor node via the F1 interface.

[0084]

[0098] The DC scenario of the IAB node in FIG. 10 and FIG. 11 is used as an example. FIG. 10 is a diagram of a CP-UP separation scenario in an EN-DC scenario according to an embodiment of the present application. FIG. 11 is a diagram of a CP-UP separation scenario in an NR-DC scenario according to an embodiment of the present application. As shown in FIG. 10, an IAB node (e.g., IAB node 2 or IAB node 1 in FIG. 10) supports dual connectivity of 4G and 5G networks, i.e., E-UTRAN NR Dual Connectivity (EN-DC) mode. The LTE base station eNB is a master base station (Master eNB, MeNB), which provides an LTE air interface (LTE Uu) connection to the IAB node and establishes an S1 interface with a 4G evolved packet core network (Evolved Packet Core, EPC) to perform user plane and control plane transmission. The CG on the LTE side is the MCG. The IAB donor (e.g., gNB) is a secondary base station that provides NR air interface (NR Uu) connectivity to the IAB node and establishes an S1 interface with the core network EPC to perform user plane transmission. The CG on the NR side is the SCG. The F1-C and F1-U services of an IAB node (e.g., IAB node 2 or IAB node 1 in Fig. 10) reach the IAB donor (e.g., gNB) separately via different routes. As shown in Fig. 11, the IAB node 2 establishes a connection to the network only through the New Radio (NR) air interface. In other words, the IAB node 2 is connected to two parent nodes in an NR-DC format. The two parent nodes can act as a Master Node (MN) or a Secondary Node (SN) for the IAB node 2, respectively. The CG configured on the MN side is the MCG, and the CG configured on the SN side is the SCG. The F1-C and F1-U services of IAB Node 2 reach the IAB donor (gNB) separately via different routes.

[0085]

[0099] Regardless of the CP-UP separation scenario in the EN-DC scenario shown in Figure 10 or the CP-UP separation scenario in the NR-DC scenario shown in Figure 11, for the IAB node, when the CG for carrying F1-C service is MCG and link RLF occurs, the normal operation of the SCG for carrying F1-U service is not immediately affected, and accordingly, the F1-U service of the child node forwarded by the IAB node is not immediately affected. In this case, based on the aforementioned trigger condition "RLF occurs in the backhaul link of the master cell group, and no MCG fast recovery of the master cell group is performed (no MCG fast recovery), which causes the IAB node to initiate RRC re-establishment", the IAB node sends RLF indication information to its child node. As a result, the child nodes stop routing data to the IAB node, causing data packet stacking, link congestion, and excessively long latency for the child nodes (in which case the amount of data traffic associated with the user plane is usually much higher than the amount of data traffic in the control plane).

[0086] Furthermore, if the cell group carrying the F1-U service is an SCG and the link RLF occurs only in the SCG, based on the aforementioned trigger condition that "RLF occurs in the backhaul links (BLs) of two cell groups (CGs) of the IAB node, causing the IAB node to initiate RRC re-establishment", the IAB node will not send RLF indication information to the child node, and the child node will continue to schedule data to the IAB node normally, which will cause data packet stacking, link congestion, and excessively long latency for the IAB node.

[0087]

[0100] Therefore, the present application provides a radio link failure indication method according to the following embodiments, which is helpful in improving the stability and reliability of data transmission in an IAB network, and alleviating the problems of data packet stacking, link congestion, and excessively long latency of an IAB node. Hereinafter, the radio link failure indication method in the present application will be described in detail using several embodiments.

[0088]

[0101] First, a communication system architecture to which the radio link failure indication method in the present application is applied will be described. The radio link failure indication method in the present application is mainly for an IAB network communication system in a DC type networking, for example, an IAB network communication system in an EN-DC type networking shown in FIG. 12, or an IAB network communication system in an NR-DC type networking shown in FIG. 13.

[0089]

[0102] For example, Figure 12 is a diagram of an IAB network communication system in EN-DC type networking according to the present application. As shown in Figure 12, the IAB network communication system may include a UE, an IAB node 1, an IAB node 2, an MeNB, an IAB donor 1, an IAB donor 2, and an EPC.

[0090]

[0103] The UE can communicate with IAB donor 1 or IAB donor 2 via IAB node 2 and IAB node 1. IAB node 2 is for providing access and backhaul services to the UE. IAB node 2 may be comprised of an IAB node DU (abbreviated as IAB-DU) and an IAB node MT (abbreviated as IAB-MT). IAB node 1 is for providing access and backhaul services to a child node (here, IAB node 2). IAB node 1 may be comprised of an IAB node DU (abbreviated as IAB-DU) and an IAB node MT (abbreviated as IAB-MT).

[0091]

[0104] The IAB-DU is a distributed unit part of the IAB node (here, IAB node 1 or IAB node 2) and has the same function as the gNB-DU. An F1 interface is established between the IAB-DU and the IAB donor CU, and provides access services to UEs or child nodes of the IAB-DU.

[0092]

[0105] The IAB-MT is the mobile terminal part of an IAB node (here, IAB node 1 or IAB node 2), has UE functionality, and provides data backhaul services to child nodes of the IAB-MT.

[0093]

[0106] An IAB donor (here, IAB donor 1 or IAB donor 2) is a donor base station supporting an IAB node and may include an IAB donor CU and at least one IAB donor DU. The IAB donor CU part may include one IAB donor CU-CP (responsible for control plane services) and at least one IAB donor CU-UP (responsible for user plane services).

[0094]

[0107] The IAB Donor DU is a distributed unit part of the IAB donor (here, IAB Donor 1 or IAB Donor 2) and has similar functions to the gNB-DU, mainly implementing the functions of the L1 and L2 protocol stacks, including the functions of the PHY layer / MAC layer / RLC layer.

[0095]

[0108] The IAB donor CU is a central unit of the IAB donor (here, IAB donor 1 or IAB donor 2), has the same function as the gNB-CU, and mainly performs the functions of the PDCP layer, the SDAP layer, and the RRC layer. An F1-C interface is established between the IAB donor CU-CP and the IAB-DU, and an F1-U interface is established between the IAB donor CU-UP and the IAB-DU.

[0096]

[0109] The MeNB is an LTE base station in the EN-DC networking mode. For a UE or an IAB node (here, IAB node 1 or IAB node 2), the MeNB is a master base station (Master eNB, MeNB).

[0097]

[0110] BH is intended to represent a backhaul link. For example, the NR BH shown in FIG. 12 is specifically a connection channel between the MT portion of an IAB node (here, IAB node 1 or IAB node 2) and the DU portion of the IAB node's parent node, for backhaul transmission of UE data packets or forwarding of IAB donor data packets.

[0098]

[0111] As shown in FIG. 12, the IAB node (here, IAB node 1 or IAB node 2) supports 4G and 5G network dual connectivity, i.e., EN-DC mode. The LTE base station eNB is a MeNB, which provides the IAB node with an LTE air interface (LTE Uu) connection and establishes an S1 interface with the EPC for user plane and control plane transmission. The CG on the LTE side is the MCG. The NR base station gNB is a secondary base station, which provides the IAB node with an NR air interface (NR Uu) connection and establishes an S1 interface with the core network EPC for user plane transmission. The CG on the NR side is the SCG. Similarly, the UE also supports EN-DC. The UE is connected to the master base station eNB via an LTE Uu interface and to the secondary base station IAB node 2 via an NR Uu interface. In some embodiments, the secondary base station of the UE may be IAB donor 1 or IAB donor 2. As shown in FIG. 12, the EN-DC scenario of the IAB network may support multi-hop IAB networking. Specifically, an IAB node may be connected to IAB Donor 1 or IAB Donor 2 by using a multi-hop wireless backhaul link.

[0099]

[0112] Optionally, the EN-DC scenario of the IAB network may include a CP-UP separation scenario and a non-CP-UP separation scenario. In the CP-UP separation scenario of the EN-DC scenario, the F1-C service of the IAB node (here, IAB node 1 or IAB node 2) reaches the non-F1 terminating node (i.e., MeNB) via the LTE Uu interface channel, and then the non-F1 terminating node transmits the F1-C service to the IAB donor (here, IAB donor 1 or IAB donor 2) via the base station-to-base station interface X2, where the IAB donor may be called the F1-terminating node of the IAB node. The F1-U service of the IAB node (here, IAB node 1 or IAB node 2) is multi-hop forwarded by the IAB node to the IAB donor (here, IAB donor 1 or IAB donor 2) by using a backhaul link based on the BAP layer protocol.

[0100]

[0113] It should be noted that the communication system architecture shown in FIG. 12 is described with two IAB nodes as an example. The communication system architecture can be described using more IAB nodes, for example, three, four, or more IAB nodes, or can be described using fewer IAB nodes, for example, one IAB node. The present application is not limited to the system architecture shown in FIG. 12.

[0101]

[0114] 13 is a diagram of an IAB network communication system in NR-DC type networking according to the present application. As shown in FIG. 13, the IAB network communication system may include a UE, an IAB node 1, an IAB node 2, a gNB, an IAB donor 1, an IAB donor 2, and a 5GC.

[0102]

[0115] For descriptions of UE, IAB Node 1, IAB Node 2, IAB-DU, IAB-MT, IAB donor, IAB donor DU, and IAB donor CU, please refer to the related descriptions in Figure 12. Details will not be described again here.

[0103]

[0116] gNB is a 5G base station. For a UE or an IAB node (here, IAB node 1 or IAB node 2), the gNB may be a master node (i.e., MN or MgNB) or a secondary node (i.e., SN or SgNB) of the IAB node or UE in DC mode.

[0104]

[0117] Unlike the IAB network communication system in the EN-DC type networking shown in Figure 12, in the IAB network communication system of this embodiment, both the IAB node and the UE establish a connection to the network only via the NR air interface. The IAB node 2 is connected to two parent nodes, IAB node 1 and gNB, in the NR-DC type. The two parent nodes can function as the MN or SN of the IAB node 2, respectively. The CG configured on the MN side is the MCG, and the CG configured on the SN side is the SCG.

[0105]

[0118] Optionally, the NR-DC scenario for IAB networks may include CP-UP separation scenario and non-CP-UP separation scenario. In the CP-UP separation scenario of the NR-DC scenario, the F1-C service of the IAB node (here, IAB node1 or IAB node2) can reach the non-F1 terminating node via the NR Uu interface channel, and then the non-F1 terminating node transmits the F1-C service to the IAB donor (here, IAB donor1 or IAB donor2) via the base station-to-base station interface Xn, where the IAB donor may be called the F1-terminating node of the IAB node. The F1-U service of the IAB node (here, IAB node1 or IAB node2) is multi-hop forwarded by the IAB node to the IAB donor (here, IAB donor1 or IAB donor2) by using the backhaul link based on the BAP layer protocol.

[0106]

[0119] In NR-DC networking, the non-F1 terminating node may be an MgNB and the F1 terminating node may be an SgNB; or, the non-F1 terminating node may be an SgNB and the F1 terminating node may be an MgNB.

[0107]

[0120] It should be noted that the communication system architecture shown in FIG. 13 is described with two IAB nodes as an example. The communication system architecture can be described using more IAB nodes, for example, three, four, or more IAB nodes, or can be described using fewer IAB nodes, for example, one IAB node. The present application is not limited to the system architecture shown in FIG. 13.

[0108]

[0121] It should be further noted that the name of the F1 interface is merely an example and does not constitute any limitation on the function of the F1 interface. In 5G networks and other future networks, the F1 interface may alternatively have another name. This is not particularly limited in this embodiment of the present application. It should be further understood that the names of the messages (or signaling) transmitted between the aforementioned network elements are merely an example and do not constitute any limitation on the function of the messages.

[0109]

[0122] According to the radio link failure indication method in the present application, a first node sends a first RLF indication information to a second node, If an RLF occurs in the backhaul link of one of the two cell groups that is intended to carry FI interface user plane (F1-U) services, or When an RLF occurs in a backhaul link of a cell group of the two cell groups that is intended to carry F1-U services, and link recovery is performed; or If an RLF occurs in a backhaul link of one of the two cell groups that is configured to carry F1 interface services based on the BAP layer, or When an RLF occurs in a backhaul link of a cell group of two cell groups, the cell group being configured to carry F1 interface services based on a BAP layer, and link recovery is performed, the first node is served by the two cell groups, and the child node of the first node is the second node.

[0110] Therefore, the first node triggers the transmission of the first RLF indication information by detecting that an RLF occurs on a backhaul link in a cell group for transmitting an F1-U service, so as to improve the stability and reliability of data transmission in the IAB network. In the CP-UP separation scenario in the DC scenario, if the cell group for transmitting an F1-C service is an MCG and an RLF occurs, and the cell group for transmitting an F1-U service is an SCG and an RLF does not occur, the first node does not immediately transmit the first RLF indication information to the second node based on the triggering method of the first RLF indication information. In this way, the impact on the normal operation of the SCG for transmitting an F1-U service can be reduced. The second node can further continue to route data to the first node. This helps to reduce the problems of data packet stacking, link congestion, and excessively long latency of the second node. In addition, when the cell group for transmitting the F1-U service is an SCG and the RLF occurs only in the SCG, the first node sends the first RLF indication information to the second node according to a triggering manner of the first RLF indication information, and the second node can trigger the stop of sending data packets to the first node, or the second node can trigger a rerouting operation of the data packets routed by the first node. In this way, the problems of data packet stacking, link congestion, and excessively long latency of the first node can be alleviated.

[0111]

[0123] The transmitting of the F1 interface service based on the BAP layer includes transmitting an F1-U service and / or an F1 interface control plane (F1-C) service based on the BAP layer. In a control plane-user plane (CP-UP) separation scenario in the DC scenario, the transmitting of the F1 interface service based on the BAP layer may include transmitting an F1-U service based on the BAP layer, and the F1-C service may be transmitted based on the RRC layer (i.e., an F1-C service in the RRC). In a non-CP-UP separation scenario in the DC scenario, the transmitting of the F1 interface service based on the BAP layer may include transmitting an F1-U service and an F1-C service based on the BAP layer.

[0112]

[0124] When an RLF is detected to occur on a backhaul link in a cell group configured to transmit an F1 interface service based on the BAP, the transmission of the first RLF indication information is triggered. When an RLF is detected to occur on a backhaul link in all cell groups configured to transmit an F1 interface service based on the BAP, the first RLF indication information indicates that an RLF has occurred on a node-granularity link between the first node and the second node, i.e., indicates that an RLF has occurred across the backhaul links between the first node and the second node.

[0113]

[0125] In some cases, an occurrence of an RLF on a backhaul link in a cell group for carrying F1-U services may be understood as the cell group for carrying F1-U services failing. An occurrence of an RLF on a backhaul link in a cell group for carrying F1-U services and link recovery being performed may be understood as the cell group for carrying F1-U services failing and link recovery being performed. Link recovery in this embodiment of the present application may include fast recovery.

[0114]

[0126] For example, in the case of the IAB network communication system shown in FIG. 12 or FIG. 13, the first node in this embodiment of the present application may be IAB node 1 in FIG. 12 or FIG. 13, and the second node may be IAB node 2 in FIG. 12 or FIG. 13.

[0115]

[0127] The two cell groups may include an MCG and an SCG, the first node is served by the MCG and the SCG, and the child node of the first node is the second node. The communication method in the present application may include a number of different implementations. The different implementations are described below with reference to the accompanying drawings.

[0116]

[0128] Implementation 1: When the SCG is for transmitting an F1-U service, and an RLF does not occur in the MCG and an RLF occurs in the SCG, the first node sends a first RLF indication information to the second node.

[0117]

[0129] Implementation 1 of the wireless link failure indication method in the present application will be described with reference to FIG. 14. FIG. 14 is a flowchart of the wireless link failure indication method according to the present application. As shown in FIG. 14, the indication method may include the following steps:

[0130] S1401: A first node determines that a first trigger condition is satisfied, where the first trigger condition includes: an SCG is for transmitting an F1-U service, an RLF is not occurring in an MCG, and an RLF is occurring in an SCG.

[0118]

[0131] For example, the first node may be IAB node 1 in Figure 12, and the second node may be IAB node 2 in Figure 12. The MeNB configures the MCG of the first node, and the IAB donor 1 configures the SCG of the first node.

[0119]

[0132] For example, the first node may be IAB node 1 in Figure 13, and the second node may be IAB node 2 in Figure 13. The gNB configures the MCG of the first node, and the IAB donor 1 configures the SCG of the first node. Alternatively, the gNB configures the SCG of the first node, and the IAB donor 1 configures the MCG of the first node.

[0120]

[0133] No RLF at the MCG means no RLF on the backhaul link of the MCG, and RLF at the SCG means RLF on the backhaul link of the SCG, which may also be referred to as SCG failure.

[0121]

[0134] The occurrence of an RLF in the SCG in the first trigger condition may specifically include: an RLF occurs in the SCG and link recovery is performed.

[0122]

[0135] In the first trigger condition, the SCG is for transmitting the F1-U service may specifically include that the SCG is for transmitting the F1-U service based on the BAP, in other words, the F1-U service is transmitted in the SCG in an F1 over BAP transmission mode.

[0123]

[0136] S1402: The first node sends a first RLF indication information to the second node.

[0124]

[0137] The first node having the dual connection sends a first RLF indication to the second node by determining that a first trigger condition is satisfied. The first RLF indication may be a Type-2 RLF indication.

[0125]

[0138] The MCG may be used to carry F1-C services, or it may be used to transmit F1-U services.

[0126]

[0139] In the implementation, the MCG is only for carrying F1-C services, and the first RLF indication information indicates that an RLF has occurred on a node granular link between a first node and a second node. The occurrence of an RLF on a node granular link means that the entire BH link between the first node and the second node is unavailable. The unavailability of the entire BH link between the first node and the second node specifically means that the data packets of the second node cannot be transmitted through the first node.

[0127]

[0140] The first RLF indication information indicating that an RLF has occurred on a node granular link between the first node and the second node may include: The first RLF indication information indicates that an RLF has occurred on a node granular link between the first node and the second node, and link recovery is to be performed.

[0128]

[0141] In some embodiments, the second node receives a first RLF indication, the first RLF indication indicating that an RLF has occurred on a node granular link between the first node and the second node, or indicating that an RLF has occurred on a node granular link between the first node and the second node and link recovery is performed, and the second node may trigger a cessation of transmitting data packets to the first node based on the first RLF indication.

[0129]

[0142] In another possible implementation, the MCG is also for transmitting F1-U services, and the first RLF indication information may include a first BAP address, a first routing ID, or a first path ID. The first routing ID may be formed by the first BAP address and the first path ID. The first node may determine the content included in the first RLF indication information based on various cases.

[0130]

[0143] When the first RLF indication information includes a first BAP address, a first routing ID, or a first path ID, different from indicating that an entire backhaul link between the first node and the second node is unavailable, a first data packet of the second node cannot be transmitted through the first node, where: the routing identifier carried in the first data packet is a first routing ID, or a route identifier within a routing identifier carried in the first data packet is the first route ID, or The BAP address in the routing identifier carried in the first data packet is the first BAP address.

[0131]

[0144] For example, the first node determines that all paths through the first node to the destination node are unavailable. The first RLF indication may include a first BAP address, where the first BAP address is a BAP address of the destination node.

[0132]

[0145] For example, the first node determines that a route with a first route ID is unavailable for all routes through the first node to the destination node. The first RLF indication information may include the first route ID.

[0133]

[0146] For example, the first node determines that a route of the first routing ID is unavailable for all routes through the first node to the destination node, and the first RLF indication information may include the first routing ID.

[0134]

[0147] After receiving the first RLF indication information, the second node may skip sending the first data packet to the first node, in which case: the routing identifier carried in the first data packet is a first routing ID, or a route identifier within a routing identifier carried in the first data packet is the first route ID, or The BAP address in the routing identifier carried in the first data packet is the first BAP address. For example, the second node may trigger a rerouting operation of the data packet routed by the first node to skip transmitting the first data packet to the first node.

[0135]

[0148] In this embodiment, when the SCG is for transmitting F1-U services, and an RLF does not occur in the MCG and an RLF occurs in the SCG, the first node sends a first RLF indication information to the second node to improve the stability and reliability of data transmission in the IAB network.

[0136] In the case of the CP-UP separation scenario in the DC scenario, if the cell group for carrying F1-C services is an MCG and RLF occurs, and the cell group for carrying F1-U services is an SCG and RLF does not occur, the first node does not immediately send the first RLF indication information to the second node according to the triggering manner of the first RLF indication information. In this way, the impact on the normal operation of the SCG for carrying F1-U services can be reduced. The second node can further continue to route data to the first node. This can reduce the problems of data packet stacking, link congestion, and excessively long latency of the second node.

[0137] Furthermore, when the cell group for transmitting the F1-U service is an SCG, and the RLF only occurs in the SCG, the first node sends a first RLF indication information to the second node according to a triggering method of the first RLF indication information; The second node may trigger a cessation of sending data packets to the first node, or The second node can trigger a rerouting operation of the data packets routed by the first node, thus alleviating the problems of data packet stacking, link congestion, and excessively long latency of the first node.

[0138]

[0149] Implementation 2: When the MCG is for transmitting F1-U services, an RLF occurs in the MCG, and a link recovery is performed, the first node sends a first RLF indication information to the second node.

[0139]

[0150] Implementation 2 of the wireless link failure indication method in the present application will be described with reference to FIG. 15. FIG. 15 is a flowchart of the wireless link failure indication method according to the present application. As shown in FIG. 15, the indication method may include the following steps:

[0151] S1501: A first node determines that a second trigger condition is satisfied, where the second trigger condition includes: an MCG is for transmitting an F1-U service, an RLF occurs in the MCG, and link recovery is performed.

[0140]

[0152] For example, the first node may be IAB node 1 in Figure 13, and the second node may be IAB node 2 in Figure 13. The gNB configures the MCG of the first node, and the IAB donor 1 configures the SCG of the first node. Alternatively, the gNB configures the SCG of the first node, and the IAB donor 1 configures the MCG of the first node.

[0141]

[0153] RLF at the MCG means that the backhaul link of the SCG is experiencing RLF, which may also be referred to as an SCG failure.

[0142]

[0154] In the second trigger condition, the MCG is for transmitting the F1-U service may specifically include that the MCG is for transmitting the F1-U service based on the BAP, in other words, the F1-U service is transmitted in the MCG in an F1 over BAP transmission mode.

[0143]

[0155] S1502: The first node sends a first RLF indication information to the second node.

[0144]

[0156] The first node having the dual connection sends a second RLF indication to the second node by determining that the second trigger condition is satisfied. The first RLF indication may be a Type-2 RLF indication.

[0145]

[0157] The SCG may be used to carry F1-C services, or it may be used to transmit F1-U services.

[0146]

[0158] In the implementation, the SCG is only for carrying F1-C services, and the first RLF indication information indicates that an RLF occurs on a node granular link between a first node and a second node. The occurrence of an RLF on a node granular link means that the entire BH link between the first node and the second node is unavailable.

[0147]

[0159] The first RLF indication information indicating that an RLF has occurred on a node granular link between the first node and the second node may include: The first RLF indication information indicates that an RLF has occurred on a node granular link between the first node and the second node, and link recovery is to be performed.

[0148]

[0160] In some embodiments, the second node receives a first RLF indication, the first RLF indication indicating that an RLF has occurred on a node granular link between the first node and the second node, or indicating that an RLF has occurred on a node granular link between the first node and the second node and link recovery is performed, and the second node may trigger a cessation of transmitting data packets to the first node based on the first RLF indication.

[0149]

[0161] In another possible implementation, the SCG is also for carrying F1-U services, and no RLF occurs in the SCG, and the first RLF indication information may include a first BAP address, a first routing ID, or a first path ID. The first routing ID may be formed by the first BAP address and the first path ID. The first node may determine the content included in the first RLF indication information based on various cases.

[0150]

[0162] For example, the first node determines that all paths through the first node to the destination node are unavailable. The first RLF indication may include a first BAP address, where the first BAP address is a BAP address of the destination node.

[0151]

[0163] For example, the first node determines that a route with a first route ID is unavailable for all routes through the first node to the destination node. The first RLF indication information may include the first route ID.

[0152]

[0164] For example, the first node determines that a route of the first routing ID is unavailable for all routes through the first node to the destination node, and the first RLF indication information may include the first routing ID.

[0153]

[0165] After receiving the first RLF indication information, the second node may skip sending the first data packet to the first node, in which case: the routing identifier carried in the first data packet is a first routing ID, or a route identifier within a routing identifier carried in the first data packet is the first route ID, or The BAP address in the routing identifier carried in the first data packet is the first BAP address. For example, the second node may trigger a rerouting operation of the data packet routed by the first node to skip transmitting the first data packet to the first node.

[0154]

[0166] In this embodiment, the MCG is for transmitting F1-U services, and when the MCG experiences an RLF and performs link recovery, the first node sends a first RLF indication to the second node to improve the stability and reliability of data transmission in the IAB network. Compared with the case where the RLF indication is triggered when the MCG experiences an RLF and does not perform fast recovery, the present application uses a second trigger condition to trigger the RLF indication, so that the second node can receive the indication in advance, which can reduce the problems of data packet stacking, link congestion, and excessively long latency of the first node or the second node.

[0155]

[0167] In the case of the CP-UP separation scenario in the DC scenario, if the cell group for carrying F1-C services is an MCG and RLF occurs, and the cell group for carrying F1-U services is an SCG and RLF does not occur, the first node does not immediately send the first RLF indication information to the second node according to the triggering manner of the first RLF indication information. In this way, the impact on the normal operation of the SCG for carrying F1-U services can be reduced. The second node can further continue to route data to the first node. This can reduce the problems of data packet stacking, link congestion, and excessively long latency of the second node.

[0156]

[0168] In some embodiments, the first node may be configured with a first trigger condition and a second trigger condition and is capable of sending a first RLF indication information to the second node if either the first trigger condition or the second trigger condition is satisfied.

[0157]

[0169] Implementation 1 and Implementation 2 of the radio link failure indication method in this application are applied to a CP-UP separation scenario in an EN-DC scenario of an IAB network shown in Figure 12. The IAB node 1 in Figure 12 functions as a first node, and the IAB node 2 in Figure 12 functions as a second node. The MeNB configures an MCG, the IAB donor 1 configures an SCG, the MCG is for carrying F1-C services, and the SCG is for carrying F1-U services. For specific implementations, please refer to the description of the embodiment of the method shown in Figure 16.

[0158]

[0170] 16 is a flow chart of a wireless link failure indication method according to the present application. As shown in FIG. 16, the indication method may include the following steps:

[0159]

[0171] S1601: When IAB node 1 detects that an RLF has occurred in the MCG and an RLF has not occurred in the SCG, the first IAB node does not send a first RLF indication information to IAB node 2 during a first period.

[0160]

[0172] For example, FIG. 17A is a diagram of an RLF scenario according to the present application. As shown in FIG. 17A, in the RLF scenario, an RLF occurs in a backhaul link between IAB node 1 and MeNB. Specifically, an RLF occurs in a backhaul link of MCG, and an RLF does not occur in a backhaul link between IAB node 1 and IAB donor 1. That is, an RLF does not occur in a backhaul link of SCG. Therefore, the current RLF scenario does not satisfy the above-mentioned first trigger condition or the second trigger condition, and IAB node 1 does not immediately send a first RLF indication information to IAB node 2. For example, IAB node 1 does not send a first RLF indication information to IAB node 2 in a first period. The first period can be flexibly set based on requirements.

[0161]

[0173] Therefore, when an RLF occurs on a link to the MeNB or an RLF occurs on an MCG for transmitting an F1-C service, the IAB node 1 does not immediately transmit the first RLF indication information to the IAB node 2. The link to the MeNB may be understood as a link on which an LTE Uu interface is located, an LTE leg link, or a link to a non-F1 terminating node. The MCG for transmitting an F1-C service may include an MCG for transmitting an F1-C service based on an RRC protocol layer.

[0162]

[0174] S1602: The IAB node 1 detects that an RLF has occurred in the SCG and an RLF has not occurred in the MCG, and the IAB node 1 sends a first RLF indication information to the IAB node 2.

[0163]

[0175] For example, Figure 17B is a diagram of an RLF scenario according to the present application. As shown in Figure 17B, in the RLF scenario, an RLF occurs in the backhaul link between IAB node 1 and IAB donor 1. Specifically, an RLF occurs in the backhaul link of the SCG, and an RLF does not occur in the backhaul link between IAB node 1 and MeNB. That is, an RLF does not occur in the backhaul link of the MCG. Therefore, the current RLF scenario satisfies the first trigger condition described above, and IAB node 1 sends a first RLF indication information to IAB node 2.

[0164]

[0176] For a specific description of the first RLF indication information, please refer to the description of S1402 in Fig. 14. The details will not be described again here.

[0165]

[0177] In this embodiment, when the cell group carrying the F1-C service is an MCG and an RLF occurs, and the cell group carrying the F1-U service is an SCG and an RLF does not occur, the first node does not immediately send the first RLF indication information to the second node according to the triggering method of the first RLF indication information. In this way, the impact on the normal operation of the SCG carrying the F1-U service can be reduced. The second node can further continue to route data to the first node. This can reduce the problems of data packet stacking, link congestion, and excessively long latency of the second node.

[0166] When the cell group for transmitting the F1-U service is an SCG, and the RLF only occurs in the SCG, the first node sends a first RLF indication information to the second node according to a triggering method of the first RLF indication information; The second node may trigger a cessation of sending data packets to the first node, or The second node can trigger a rerouting operation of the data packets routed by the first node, thus alleviating the problems of data packet stacking, link congestion, and excessively long latency of the first node.

[0167]

[0178] Implementation 1 and Implementation 2 of the radio link failure indication method in this application are applied to the NR-DC scenario of the IAB network shown in FIG. 13. The IAB node 1 in FIG. 13 functions as a first node, and the IAB node 2 in FIG. 13 functions as a second node. The gNB configures the MCG, and the IAB donor 1 configures the SCG. Alternatively, the gNB configures the SCG, and the IAB donor 1 configures the MCG. This embodiment is described using an example in which the gNB configures the SCG, and the IAB donor 1 configures the MCG. For specific implementation, please refer to the description of the embodiment of the method shown in FIG. 18.

[0168]

[0179] 18 is a flow chart of a wireless link failure indication method according to the present application. As shown in FIG. 18, the indication method may include the following steps:

[0169]

[0180] S1801: When IAB node 1 detects that the SCG is for transmitting F1-C services, an RLF occurs in the SCG, and an RLF does not occur in the MCG, the first IAB node does not send a first RLF indication information to IAB node 2 during a first period.

[0170]

[0181] For example, FIG. 19A is a diagram of an RLF scenario according to the present application. As shown in FIG. 19A, in the RLF scenario, an RLF occurs in a backhaul link between IAB node 1 and a gNB. Specifically, an RLF occurs in a backhaul link of an SCG, and an RLF does not occur in a backhaul link between IAB node 1 and IAB donor 1. That is, an RLF does not occur in a backhaul link of an MCG. Therefore, the current RLF scenario does not satisfy the above-mentioned first trigger condition or the second trigger condition, and the IAB node 1 does not immediately send a first RLF indication information to the IAB node 2. For example, the IAB node 1 does not send a first RLF indication information to the IAB node 2 in a first period. The first period can be flexibly set based on requirements.

[0171]

[0182] Therefore, when an RLF occurs on a link to a non-F1 terminating node (e.g., a gNB here) or an RLF occurs on a CG for transmitting an F1-C service (e.g., an SCG here), the IAB node 1 does not immediately send the first RLF indication information to the IAB node 2. The CG for transmitting an F1-C service may include a CG configured to transmit an F1-C service based on the RRC protocol layer.

[0172]

[0183] S1802: When IAB node 1 detects that the MCG is for transmitting F1-U services and an RLF occurs in the MCG and link recovery is performed, the IAB node 1 sends a first RLF indication information to IAB node 2.

[0173]

[0184] For example, Figure 19B is a diagram of an RLF scenario according to the present application. As shown in Figure 19B, in the RLF scenario, an RLF occurs on the backhaul link between IAB node 1 and IAB donor 1. That is, an RLF does not occur on the backhaul link of the MCG. Therefore, the current RLF scenario meets the second trigger condition described above, and IAB node 1 sends a first RLF indication information to IAB node 2.

[0174]

[0185] For a specific description of the first RLF indication information, please refer to the description of S1502 in Fig. 15. The details will not be described again here.

[0175]

[0186] In this embodiment, when the cell group carrying the F1-C service is an MCG and an RLF occurs, and the cell group carrying the F1-U service is an SCG and an RLF does not occur, the first node does not immediately send the first RLF indication information to the second node according to the triggering method of the first RLF indication information. In this way, the impact on the normal operation of the SCG carrying the F1-U service can be reduced. The second node can further continue to route data to the first node. This helps to reduce the problems of data packet stacking, link congestion, and excessively long latency of the second node.

[0176] When a cell group for transmitting an F1-U service is an MCG, and an RLF occurs in the MCG and a link recovery is performed, the first node sends a first RLF indication information to a second node according to a triggering method of the first RLF indication information; The second node may trigger a cessation of sending data packets to the first node, or The second node can trigger a rerouting operation of the data packets routed by the first node, thus alleviating the problems of data packet stacking, link congestion, and excessively long latency of the first node.

[0177]

[0187] In the above embodiment, the first node sends a first RLF indication information to the second node by detecting the first trigger condition and / or the second trigger condition. The second node can trigger to stop sending data packets to the first node or trigger a rerouting operation of the data packets routed by the first node based on the first RLF indication information, so as to alleviate the problems of data packet stacking, link congestion, and excessively long latency. Different from the above embodiment, the present application further provides the following radio link failure indication method: RLF link information or routing information is carried in the second RLF indication information, so that the second node performs a corresponding operation based on the RLF link information or routing information to alleviate the problems of data packet stacking, link congestion, and excessively long latency.

[0178]

[0188] Figure 20 is a flow chart of a radio link failure indication method according to an embodiment of the present application. Similar to the previous embodiment, a first node is served by an SCG and an MCG, and a second node is a child node of the first node. As shown in Figure 20, the indication method may include the following steps:

[0179]

[0189] S2001: A first node sends a second RLF indication information to a second node.

[0180]

[0190] For example, the first node may be IAB node 1 in Figure 12, and the second node may be IAB node 2 in Figure 12. The MeNB configures an MCG for the first node, and the IAB donor 1 configures an SCG for the first node.

[0181]

[0191] For example, the first node may be IAB node 1 in Figure 13, and the second node may be IAB node 2 in Figure 13. The gNB configures the MCG for the first node, and the IAB donor 1 configures the SCG for the first node. Alternatively, the gNB configures the SCG for the first node, and the IAB donor 1 configures the MCG for the first node.

[0182]

[0192] The second RLF indication information may be a Type-1 RLF indication, a Type-2 RLF indication, a Type-3 RLF indication, or a Type-4 RLF indication.

[0183]

[0193] A Type-1 RLF indication is an indication triggered when an RLF is detected on a backhaul link. Specifically, when a first node finds that an RLF occurs on a backhaul link, the first node sends a Type-1 RLF indication to a second node.

[0184] A Type-2 RLF indication is an indication triggered when an RLF occurs on a backhaul link and link recovery is to be performed. Specifically, when a first node finds that an RLF occurs on a backhaul link and prepares to perform link recovery, the first node sends a Type-2 RLF indication to a second node.

[0185] A Type-3 RLF indication is an indication information triggered during link recovery. Specifically, when the link of a first node recovers, the first node sends a Type-3 RLF indication to a second node.

[0186] A Type-4 RLF indication is an indication information that is triggered when an RLF occurs on a backhaul link and link recovery is detected to have failed. Specifically, when a first node detects that an RLF occurs on a backhaul link, performs link recovery, and detects that link recovery is failed, the first node sends a Type-4 RLF indication to a second node.

[0187]

[0194] In the implementation, the second RLF indication information may include RLF link information. The RLF link information may be backhaul link information to a non-F1 end node, LTE-Uu interface link information (as in the above-mentioned EN-DC scenario), backhaul link information for transmitting F1-C services, or cell group identifier information for transmitting F1-C services based on the RRC protocol layer. In the EN-DC scenario, the cell group identifier information for transmitting F1-C services based on the RRC protocol layer may be MCG identifier information for transmitting F1-C services based on the RRC protocol layer. In the NR-DC scenario, the cell group identifier information for transmitting F1-C services based on the RRC protocol layer may be MCG or SCG identifier information for transmitting F1-C services based on the RRC protocol layer.

[0188]

[0195] For example, when a first node detects the RLF scenario shown in FIG. 17A, the second RLF indication information sent by the first node to the second node may include RLF link information.

[0189]

[0196] In another possible implementation, the second RLF indication information may include routing information, which may include a first BAP address, a first routing ID, or a first path ID.

[0190]

[0197] For example, when a first node detects the RLF scenario shown in FIG. 17B, the second RLF indication information sent by the first node to the second node may include routing information.

[0191]

[0198] 2002: The second node does not trigger a scheduling stop and / or a rerouting operation of the upstream data packet based on the RLF link information, or the second node triggers a rerouting operation of the upstream data packet based on the routing information.

[0192]

[0199] For example, if the second RLF indication information received by the second node includes RLF link information, the second node does not trigger a stop scheduling and / or rerouting operation of upstream data packets based on the RLF link information. Optionally, if the second RLF indication information is a Type-3 RLF indication, the second node does not stop rerouting of upstream data packets caused by an RLF occurring on another link.

[0193]

[0200] For example, if the second RLF indication information received by the second node includes routing information, the second node triggers a re-routing operation of the upstream data packet based on the routing information, for example, rewriting the BAP routing ID in the upstream data packet.

[0194]

[0201] In this embodiment, the first node sends a second RLF indication information to the second node, and if the second RLF indication information includes RLF link information, the second node does not trigger a scheduling stop and / or re-routing operation of the upstream data packet based on the RLF link information, so as to mitigate the problems of data packet stacking, link congestion, and excessively long latency of the second node caused by the unnecessary RLF indication. If the second RLF indication information includes routing information, the second node triggers a re-routing operation of the upstream data packet based on the routing information, so as to mitigate the problems of data packet stacking, link congestion, and excessively long latency of the first node.

[0195]

[0202] Based on the similar technical concept mentioned above, an embodiment of the present application provides a communication device. The communication device may be a first node or a second node in any possible design solution of the method of the above embodiment. The communication device includes at least one corresponding unit configured to perform a method step, process, or operation performed by the first node or the second node in the above communication method. The at least one unit may be arranged in one-to-one correspondence with the method step, process, or operation performed by the first node or the second node. These units may be implemented using a computer program, may be implemented using a hardware circuit, or may be implemented by using a combination of a computer program and a hardware circuit.

[0196]

[0203] According to the above method, FIG. 21 is a diagram of a communication device 2100 according to an embodiment of the present application.

[0197]

[0204] The apparatus 2100 may be a relay forwarding node having access and backhaul functions, or may be a chip or circuit, for example a chip or circuit capable of being disposed in a relay forwarding node having access and backhaul functions.

[0198]

[0205] The apparatus 2100 may include a processing unit 2110 (eg, including a processor or a communication processor) and a transceiver unit 2130 .

[0199]

[0206] Optionally, the transceiver unit 2130 may be implemented using a transceiver, transceiver-related circuitry, or interface circuitry.

[0200]

[0207] In some embodiments, the apparatus 2100 is used as a first node, the first node being served by a first master cell group MCG and a first secondary cell group SCG, a child node of the first node being a second node, and the processing unit 2110 is configured to: send RLF indication information to the second node via the transceiver unit when the first SCG is for carrying F1 interface user plane services, and when a radio link failure RLF does not occur in the first MCG and an RLF occurs in the first SCG.

[0201]

[0208] Optionally, the processing unit 2110 is configured to send RLF indication information to the second node via the transceiver unit 2130 when the first SCG is for carrying F1 interface user plane services, a radio link failure RLF has not occurred in the first MCG, and an RLF has occurred in the first SCG, including: the processing unit 2110 is configured to send RLF indication information to the second node via the transceiver unit 2130 when the first SCG is for carrying F1 interface user plane services, a radio link failure RLF has not occurred in the first MCG, an RLF has occurred in the first SCG, and link recovery is performed.

[0202]

[0209] Optionally, the first SCG may be intended to carry F1 interface user plane services: The first SCG includes being configured to carry F1 interface user plane services based on a backhaul adaptation protocol (BAP) layer.

[0203]

[0210] Optionally, the first MCG is only for carrying F1 interface control plane services and the RLF indication information indicates that RLF is occurring on the node granular link between the first node and the second node.

[0204]

[0211] Optionally, the RLF indication information may indicate that RLF is occurring on a node granularity link between the first node and the second node: The RLF indication information indicates that an RLF has occurred on a node granular link between a first node and a second node, and link recovery is to be performed.

[0205]

[0212] Optionally, the first MCG is also for carrying F1 interface user plane services, and the RLF indication information includes a first BAP address, a first routing ID, or a first path ID.

[0206]

[0213] Optionally, the processing unit 2110 is configured to determine that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first BAP address, which is a BAP address of the destination node; the processing unit 2110 is configured to determine that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first route ID; or, the processing unit 2110 is configured to determine that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first routing ID.

[0207]

[0214] In some embodiments, the apparatus 2100 is used as a first node, the first node being served by a first master cell group MCG and a first secondary cell group SCG, a child node of the first node being a second node, and the processing unit 2110 is configured to send RLF indication information to the second node via the transceiver unit 2130 when the first MCG is for transmitting F1 interface user plane services, a radio link failure RLF occurs in the first MCG, and link recovery is performed.

[0208]

[0215] Optionally, the first MCG may be intended to carry F1 interface user plane services: The first MCG includes being configured to carry F1 interface user plane services based on a backhaul adaptation protocol (BAP) layer.

[0209]

[0216] Optionally, the first SCG is dedicated to carrying F1 interface control plane services and the RLF indication information indicates that RLF is occurring on the node granular link between the first node and the second node.

[0210]

[0217] Optionally, the first SCG is also for carrying F1 interface user plane services, no RLF occurs in the first SCG, and the RLF indication information includes a first BAP address, a first routing ID, or a first path ID.

[0211]

[0218] Optionally, the processing unit 2110 is configured to determine that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first BAP address, which is a BAP address of the destination node; the processing unit 2110 is configured to determine that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first route ID; or, the processing unit 2110 is configured to determine that all routes through the first node to the destination node are unavailable, and the RLF indication information includes a first routing ID.

[0212]

[0219] The units in the above embodiments may be called modules, circuits, or components.

[0213]

[0220] For the concept, description, detailed description and other steps of the device 2100 related to the technical solution provided in the embodiments of the present application, please refer to the description of the content of the above method or other embodiments, and the details will not be described again here.

[0214]

[0221] FIG. 22 is a structural diagram of a communication device 2200 according to an embodiment of the present application. The communication device 2200 may be configured to implement the functionality of a relay node (e.g., a first node) having access and backhaul functions in the aforementioned method. As shown in FIG. 22, the communication device 2200 includes one or more processors 2201, and optionally further includes an interface 2202. When associated program instructions are executed in the at least one processor 2201, the device 2200 can realize the radio link failure indication method and any possible design of the radio link failure indication method provided in any of the aforementioned embodiments. Alternatively, the processor 2201 is configured to realize the radio link failure indication method and any possible design of the radio link failure indication method provided in any of the aforementioned embodiments using logic circuits or by executing code instructions. The interface 2202 may be configured to receive and transmit program instructions to the processor, or the interface 2202 may be used by the device 2200 to communicate and interact with another communication device, for example to exchange control signaling and / or service data. For example, the interface 2202 may be configured to: receive and transmit signals from devices other than the device 2200 to the processor 2201, or transmit signals from the processor 2201 to communication devices other than the device 2200. The interface 2202 may be a code and / or data read / write interface circuit, or the interface 2202 may be a signal transmission interface circuit between the communication processor and a transceiver, or a pin of a chip. Optionally, the communication device 2200 may further include at least one memory 2203, which may be configured to store the required associated program instructions and / or data. Optionally, the device 2200 may further include a power supply circuit 2204. The power supply circuit 2204 can be configured to provide power to the processor 2201 .The power supply circuit 2204 and the processor 2201 may be located in the same chip, or the power supply circuit 2204 may be located in a chip separate from the chip in which the processor 2201 is located. Optionally, the device 2200 may further include a bus 2205, and parts in the device 2200 may be interconnected via the bus 2205.

[0215]

[0222] It should be understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or the processor may be another 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, etc. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc.

[0216]

[0223] It should be further understood that the memory in the embodiments of the present application may be volatile or non-volatile memory, or may include volatile and non-volatile memory. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory may be random access memory (RAM) used as an external cache. By way of example, and not limitation, many forms of random access memory (RAM) are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (synchlink DRAM, SLDRAM), or direct Rambus random access memory (DR RAM).

[0217]

[0224] The power supply circuit in the embodiments of the present application includes, but is not limited to, at least one of a power supply line, a power supply subsystem, a power management chip, a power consumption management processor, or a power consumption management control circuit.

[0218]

[0225] The transceiver device, interface, or transceiver in the embodiments of the present application may include a separate transmitter and / or a separate receiver, or the transmitter and receiver may be integrated. The transceiver device, interface, or transceiver may operate under the direction of a corresponding processor. Optionally, the transmitter may correspond to a transmitter machine in a physical device, and the receiver may correspond to a receiver machine in a physical device.

[0219]

[0226] It will be clearly understood by those skilled in the art that for convenience and concise description, the division of the above functional modules is used as an example for description. In actual application, the above functions can be allocated and implemented into various functional modules according to requirements, that is, the internal structure of the device is divided into various functional modules to implement all or part of the above functions. For detailed operation processes of the above systems, devices, and units, please refer to the corresponding processes in the above method embodiments. Details will not be described again here.

[0220]

[0227] In the embodiments of the present application, it should be understood that the disclosed system, device, and method may be implemented in other ways. For example, the embodiment of the device described is merely an example. For example, the division into multiple modules or units is merely a logical division of functions, and may be divided in other ways in actual implementation. For example, multiple units or components may be combined or integrated into another system, and some functions may be ignored or not performed. Furthermore, the illustrated or described mutual couplings or direct couplings or communication connections may be implemented through some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electrical, mechanical, or other forms.

[0221]

[0228] Those skilled in the art will recognize that in combination with the examples described in the embodiments disclosed herein, the unit or algorithm process may be implemented by hardware, software, or a combination of software and hardware. Whether a function is performed by hardware or software depends on the design constraints of a specific application and technical solution. Those skilled in the art may use various methods to implement the described functions for each specific application, but the implementation should not be considered to go beyond the scope of the present application.

[0222]

[0229] In this application, "implemented by software" may mean that a processor reads and executes program instructions stored in a memory to realize the functions corresponding to the aforementioned modules or units. The processor is a processing circuit having the function of executing program instructions, and includes, but is not limited to, at least one of the following types of processing circuits capable of executing program instructions, such as a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a microcontroller unit (MCU), or an artificial intelligence processor. In some other embodiments, the processor may further include circuits having another processing function (e.g., hardware circuits used for hardware acceleration, buses, and interface circuits). The processor may be provided in the form of an integrated chip. For example, the processor may be provided in the form of an integrated chip whose processing function only includes the function of executing software instructions; or the processor may be provided in the form of a system-on-a-chip (SoC). Specifically, in one chip, in addition to a processing circuit (usually called a "core") capable of executing program instructions, another hardware circuit configured to perform a specific function is further included (of course, the hardware circuit may be implemented independently based on an ASIC or an FPGA). Accordingly, the processing function may further include various hardware acceleration functions (such as AI calculations, encoding and decoding, compression and decompression, etc.) in addition to the function of executing software instructions.

[0223]

[0230] In this application, "implemented by hardware" means that the functions of the aforementioned modules or units are implemented by a hardware processing circuit that does not have the function of processing program instructions. The hardware processing circuit may include individual hardware components or may be an integrated circuit. To reduce power consumption and size, integrated circuits are usually used for implementation. The hardware processing circuit may include an ASIC, or a programmable logic device (PLD). The PLD may further include an FPGA, a complex programmable logic device (CPLD), etc. These hardware processing circuits may be independently packaged semiconductor chips (e.g., packaged in an ASIC), or may be integrated with other circuits (such as a CPU or DSP) and then packaged in a semiconductor chip. For example, multiple hardware circuits and a CPU may be formed on a single silicon base and packaged separately into a chip, in which case the chip may be referred to as an SoC; or, circuits configured to implement FPGA functions and a CPU may be formed on a silicon base and packaged separately into a chip, in which case the chip may be referred to as a system-on-a-programmable-chip (SoPC).

[0224]

[0231] When the present application is implemented using software, hardware, or a combination of software and hardware, the present application may be implemented by using various software and hardware, and is not limited to only one type of software or hardware. For example, one of the modules or units may be implemented by a CPU, and another module or unit may be implemented by a DSP. Similarly, when hardware is used for implementation, one of the modules or units may be implemented by an ASIC, and another module or unit may be implemented by an FPGA. Of course, it is not limited that some or all of the modules or units are implemented by using the same type of software (e.g., via a CPU) or the same type of hardware (e.g., via an ASIC). Furthermore, those skilled in the art should know that software is usually more flexible but has lower performance than hardware, and the opposite is true for hardware. Therefore, those skilled in the art can select software, hardware, or a combination thereof for implementation based on actual requirements.

[0225]

[0232] In the above embodiments, the description of each embodiment has its own focus. For parts not described in detail in the embodiments, reference can be made to the relevant descriptions of other embodiments. The embodiments of the present application can be combined, or some technical features of the embodiments can be separated from a specific embodiment or combined with the prior art to solve the technical problems in the embodiments of the present application.

[0226]

[0233] In the embodiments of the present application, the units described as separate components may or may not be physically separate, and the components illustrated as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of the units may be selected according to actual requirements to achieve the objectives of the solutions of the embodiments of the present application.

[0227]

[0234] Furthermore, the functional units in the embodiments of the present application may be integrated into one processing unit, each unit may exist physically alone, or two or more units may be integrated into one unit. The integrated unit may be implemented in the form of hardware or a software functional unit.

[0228]

[0235] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application may be essentially, or the part that contributes to the prior art, or all or part of the technical solution may be implemented in the form of a software product. The computer software product may be stored in a storage medium and include some instructions for instructing a computer device, such as a personal computer, a server, or a network device, or a processor, to perform all or part of the operations of the method described in the embodiments of the present application. The aforementioned storage medium may include any medium or computer-readable storage medium capable of storing program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0229]

[0236] In the description of this application, terms such as "first", "second", "S101", "S102" are used merely for distinction and explanation, and to facilitate the organization of this document. Different sequences or numbers do not have a specific technical meaning, and cannot be understood as indicating or implying a relative importance, or indicating or implying a sequence of execution of operations.

[0230]

[0237] The term "and / or" in this application only describes the associative relationship of related objects and indicates that three relationships may exist. For example, "A and / or B" may indicate three cases: only A is present; or both A and B are present; or only B is present. A and B may be singular or plural. Furthermore, the character " / " in this specification indicates an "or" relationship between related objects.

[0231]

[0238] In this application, "transmission" may include three cases: data transmission, data reception, or data transmission and data reception. In this application, "data" may include service data and / or signaling data.

[0232]

[0239] In this application, the terms "comprise" or "have" and any variations thereof are intended to cover a non-exclusive inclusion, e.g., a process / method comprising a series of steps or a system / product / device comprising a series of units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to those processes / methods / products / devices.

[0233]

[0240] In the description of this application, unless otherwise specified, the quantities of nouns refer to "singular or plural", i.e., "one or more". "At least one" refers to one or more. "Comprising at least one of A, B, and C" may refer to including A, including B, including C, including A and B, including A and C, including B and C, or including A, B, and C, where A, B, and C may be singular or plural.

[0234]

[0241] The above description is merely a specific implementation of the present application, and is not intended to limit the scope of protection of the present application. Any modifications or replacements that can be easily understood by those skilled in the art within the technical scope disclosed in the present application shall be included in the scope of protection of the present application.

Claims

1. 1. A method of communication, comprising: a first node served by a first master cell group (MCG) and a first secondary cell group (SCG), a child node of the first node being a second node, the method comprising: When the first SCG is for transmitting an F1 interface user plane service, and a radio link failure (RLF) does not occur in the first MCG and an RLF occurs in the first SCG, the first node sends an RLF indication information to the second node; The method includes:

2. 2. The method according to claim 1, wherein the first SCG is for carrying an F1 interface user plane service, and when a radio link failure (RLF) does not occur in the first MCG and an RLF occurs in the first SCG, the step of the first node sending an RLF indication information to the second node comprises: When the first SCG is for carrying an F1 interface user plane service, a radio link failure (RLF) does not occur in the first MCG, an RLF occurs in the first SCG, and a link recovery is performed, the first node sending an RLF indication information to the second node; The method includes:

3. 3. The method according to claim 1 or 2, wherein the first SCG is for carrying F1 interface user plane services, comprising: The method includes the first SCG being for transmitting the F1 interface user plane services based on a Backhaul Adaptation Protocol (BAP) layer.

4. 4. The method according to claim 1, wherein the first MCG is only for carrying F1 interface control plane services, and the RLF indication information indicates that an RLF is occurring on a node granular link between the first node and the second node.

5. 5. The method of claim 4, wherein the RLF indication information indicates that RLF is occurring on a node granular link between the first node and the second node, comprising: The method of claim 1, wherein the RLF indication information indicates that an RLF has occurred on a node granular link between the first node and the second node and that link recovery is to be performed.

6. 4. The method according to claim 1, wherein the first MCG is also for carrying the F1 interface user plane service, and the RLF indication information includes a first BAP address, a first routing identifier Routing ID, or a first path identifier Route ID.

7. 7. The method of claim 6 further comprising: determining by the first node that all paths through the first node to a destination node are unavailable, the RLF indication information including the first BAP address, the first BAP address being a BAP address of the destination node; The method includes:

8. 1. A method of communication, comprising: a first node served by a first master cell group (MCG) and a first secondary cell group (SCG), a child node of the first node being a second node, the method comprising: the first MCG is for transmitting an F1 interface user plane service, and when a radio link failure (RLF) occurs in the first MCG and link recovery is performed, the first node sends an RLF indication information to the second node; The method includes:

9. 9. The method of claim 8, wherein the first MCG is for transmitting an F1 interface user plane service, comprising: The first MCG is for transmitting the F1 interface user plane services based on a Backhaul Adaptation Protocol (BAP) layer.

10. 10. The method of claim 8 or 9, wherein the first SCG is only for carrying F1 interface control plane services, and the RLF indication information indicates that an RLF is occurring on a node granular link between the first node and the second node.

11. 10. The method according to claim 8 or 9, wherein the first SCG is also for carrying the F1 interface user plane service, no RLF has occurred in the first SCG, and the RLF indication information includes a first BAP address, a first routing identifier Routing ID, or a first path identifier Route ID.

12. 12. The method of claim 11 further comprising: determining by the first node that all paths through the first node to a destination node are unavailable, the RLF indication information including the first BAP address, the first BAP address being a BAP address of the destination node; determining by the first node that a route having the first route ID is unavailable among all routes through the first node to a destination node, the RLF indication information including the first route ID; or determining by the first node that a route of the first routing ID is unavailable in all routes through the first node to a destination node, the RLF indication information including the first routing ID; The method includes:

13. The first node transmits a first RLF indication to a second node. If an RLF occurs in a backhaul link of one of the two cell groups, the cell group being intended for carrying FI interface user plane F1-U services, or When an RLF occurs in a backhaul link of a cell group of the two cell groups, the cell group being for carrying F1-U services, and link recovery is performed; or If an RLF occurs in a backhaul link of one of the two cell groups, the cell group being configured to carry F1 interface services based on a backhaul adaptation protocol (BAP) layer; or When an RLF occurs in a backhaul link of a cell group of the two cell groups, the cell group being configured to carry an F1 interface service based on a BAP layer, and link recovery is performed. wherein the first node is served by the two cell groups and a child node of the first node is the second node.

14. The method of claim 13, wherein transmitting F1 interface services based on a BAP layer includes transmitting F1-U services and / or F1 interface control plane (F1-C) services based on a BAP layer.

15. A communication device for use as a first node, said first node being served by a first master cell group MCG and a first secondary cell group SCG, a child node of said first node being a second node, said communication device comprising: a processing unit configured to send an RLF indication information to the second node via a transceiver unit when the first SCG is for transmitting an F1 interface user plane service and a radio link failure (RLF) does not occur in the first MCG and an RLF occurs in the first SCG; An apparatus comprising:

16. 16. The apparatus of claim 15, wherein the first SCG is for carrying an F1 interface user plane service, and the processing unit is configured to: send an RLF indication information to the second node via a transceiver unit when a radio link failure (RLF) does not occur in the first MCG and an RLF occurs in the first SCG: the first SCG is for transmitting an F1 interface user plane service, and the processing unit is configured to send an RLF indication information to the second node via the transceiver unit when a radio link failure (RLF) has not occurred in the first MCG, an RLF has occurred in the first SCG, and link recovery is performed.

17. 17. The apparatus according to claim 15 or 16, wherein the first SCG is for transmitting F1 interface user plane services, comprising: The first SCG is for transmitting the F1 interface user plane services based on a Backhaul Adaptation Protocol (BAP) layer.

18. 18. The apparatus of claim 15, wherein the first MCG is only for carrying F1 interface control plane services, and the RLF indication information indicates that an RLF is occurring on a node granular link between the first node and the second node.

19. 20. The apparatus of claim 18, wherein the RLF indication information indicates that RLF is occurring on a node granular link between the first node and the second node, comprising: The apparatus, wherein the RLF indication information indicates that an RLF has occurred on a node granular link between the first node and the second node and that link recovery is to be performed.

20. 18. The apparatus according to any one of claims 15 to 17, wherein the first MCG is also for transmitting the F1 interface user plane service, and the RLF indication information includes a first BAP address, a first routing identifier Routing ID, or a first path identifier Route ID.

21. 21. The apparatus of claim 20, the processing unit is configured to determine that all paths through the first node to a destination node are unavailable, the RLF indication information including the first BAP address, the first BAP address being a BAP address of the destination node; the processing unit is configured to determine that a route of the first route ID is unavailable in all routes through the first node to a destination node, and the RLF indication information includes the first route ID; or The processing unit is configured to determine that a route of the first routing ID is unavailable in all routes through the first node to a destination node, and the RLF indication information includes the first routing ID.

22. A communication device for use as a first node, said first node being served by a first master cell group MCG and a first secondary cell group SCG, a child node of said first node being a second node, said communication device comprising: a processing unit configured to send an RLF indication information to the second node when the first MCG is for transmitting an F1 interface user plane service, and a radio link failure (RLF) occurs in the first MCG and a link recovery is performed; An apparatus comprising:

23. 23. The apparatus of claim 22, wherein the first MCG is for transmitting an F1 interface user plane service, comprising: The first MCG is for transmitting the F1 interface user plane service based on a Backhaul Adaptation Protocol (BAP) layer.

24. 24. The apparatus of claim 22 or 23, wherein the first SCG is only for carrying F1 interface control plane services, and the RLF indication information indicates that an RLF is occurring on a node granular link between the first node and the second node.

25. 24. The apparatus of claim 22 or 23, wherein the first SCG is also for carrying the F1 interface user plane service, no RLF has occurred in the first SCG, and the RLF indication information includes a first BAP address, a first routing identifier Routing ID, or a first path identifier Route ID.

26. 26. The apparatus of claim 25, the processing unit is configured to determine that all paths through the first node to a destination node are unavailable, the RLF indication information including the first BAP address, the first BAP address being a BAP address of the destination node; the processing unit is configured to determine that a route of the first route ID is unavailable in all routes through the first node to a destination node, and the RLF indication information includes the first route ID; or The processing unit is configured to determine that a route of the first routing ID is unavailable in all routes through the first node to a destination node, and the RLF indication information includes the first routing ID.

27. A communication device for use as a first node, the first node being served by two cell groups, a child node of the first node being a second node, the communication device comprising: transmitting a first RLF indication to a second node; If an RLF occurs in a backhaul link of one of the two cell groups, the cell group being intended for carrying FI interface user plane F1-U services, or When an RLF occurs in a backhaul link of a cell group of the two cell groups, the cell group being for carrying F1-U services, and link recovery is performed; or If an RLF occurs in a backhaul link of one of the two cell groups, the cell group being configured to carry F1 interface services based on a backhaul adaptation protocol (BAP) layer; or When an RLF occurs in a backhaul link of a cell group of the two cell groups, the cell group being configured to carry an F1 interface service based on a BAP layer, and link recovery is performed. An apparatus comprising a processing unit configured to perform the steps of:

28. 28. The apparatus of claim 27, wherein transmitting F1 interface services based on the BAP layer includes transmitting F1-U services and / or F1 interface control plane (F1-C) services based on the BAP layer.

29. A communications device, configured to perform a method according to any one of claims 1 to 14.

30. A communications device comprising at least one processor and an interface, the at least one processor being configured to call instructions from the interface and execute the instructions, the execution of the instructions by the at least one processor performing a method according to any one of claims 1 to 14.

31. 15. A computer readable storage medium containing computer instructions which, when executed on a first node, enable the first node to perform a method according to any one of claims 1 to 14.

32. A computer program product comprising program instructions which, when executed by a processor, perform the method according to any one of claims 1 to 14.

Images