Xn connection management in integrated access and backhaul networks

Abstract

Various example embodiments relate to apparatuses and methods for Xn connection management in an integrated access and backhaul (IAB) network. An integrated access and backhaul node may establish a first connection between a mobile termination component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; and transmitting the cell information to the central unit during and / or after the establishment of the second connection. The cell information indicates at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node.

Description

Technical Field

[0001] Various example embodiments described herein relate generally to communication technology, and more particularly, to apparatus and methods for Xn connection management in an Integrated Access and Backhaul (IAB) network. Background Art

[0002] Certain abbreviations that may be found in the specification and / or drawings are defined herein as follows: AMF Access and Mobility Management Function ANR Automatic Neighbor Relation CU Central Unit CP Control Plane DU Distributed Unit gNB Next Generation Node B HO Switchover IAB Integrated Access and Backhaul MT Mobile Termination NR New Radio OAM Operation Administration and Maintenance RAN Radio Access Network RRC Radio Resource Control UE User Equipment UP User Plane UPF User Plane Function

[0003] A vehicle-mounted relay (VMR) can provide high-quality communication services to user equipment (UE) on and / or around the vehicle. 5G New Radio (NR) provides support for VMR scenarios in an integrated access and backhaul (IAB) network, where a moving VMR can be implemented as an IAB node that enables wireless relay for NR access via a wireless backhaul. On the network side, the wireless backhaul terminates at a base station called an IAB donor, which provides the network with NR access to one or more IAB nodes and UEs connected to the IAB nodes. Summary of the invention

[0004] A brief summary of the invention of example embodiments is provided below to provide a basic understanding of some aspects of various embodiments. It should be noted that the present invention summary is not intended to identify the key features of the essential elements or to limit the scope of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a prelude to the more detailed description provided below.

[0005] In a first aspect, an example embodiment of an integrated access and backhaul node is provided. The integrated access and backhaul node may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, using the at least one processor, cause the integrated access and backhaul node to at least: establish a first connection between a mobile termination component in the integrated access and backhaul node and a cell served by a serving node; establish a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; and during and / or after establishing the second connection, transmit cell information to the central unit, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node.

[0006] In a second aspect, an example embodiment of a central unit for controlling one or more integrated access and backhaul nodes is provided. The central unit may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the central unit to at least: establish a second connection between a distributed unit in the integrated access and backhaul node and the central unit; during and / or after establishing the second connection, receive cell information from the integrated access and backhaul node, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node; and establish a third connection between the central unit and one or more base stations, the one or more base stations serving at least one of the one or more neighboring cells and the serving cell.

[0007] In a third aspect, an example embodiment of an integrated access and backhaul node is provided. The integrated access and backhaul node may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the integrated access and backhaul node to at least: establish a first connection between a mobile termination component in the integrated access and backhaul node and a cell served by a serving node; establish a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; and transmit cell information to the serving node. The cell information indicates the cell served by the distributed unit in the integrated access and backhaul node.

[0008] In a fourth aspect, an example embodiment of a radio access network node is provided. The radio access network node may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the radio access network node to at least: receive cell information from a mobile termination component in an integrated access and backhaul node, the cell information indicating cells served by a distributed unit in the integrated access and backhaul node; and establish a third connection between the radio access network node and a central unit for controlling the integrated access and backhaul node based on the received cell information. The central unit has a second connection with the distributed unit in the integrated access and backhaul node.

[0009] In a fifth aspect, an example embodiment of a central unit for controlling one or more integrated access and backhaul nodes is provided. The central unit may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the central unit to at least: establish a third connection between the central unit and a radio access network node; receive neighboring cell information from the radio access network node during and / or after the third connection is established between the central unit and the radio access network node, the neighboring cell information indicating one or more neighboring cells for the integrated access and backhaul node under the control of the central unit; and establish a third connection between the central unit and one or more neighboring base stations. The one or more neighboring base stations support the one or more neighboring cells indicated in the neighboring cell information.

[0010] Example embodiments of methods, apparatus, and computer program products are also provided. Such example embodiments generally correspond to the example embodiments described above, and for convenience, a repeated description thereof is omitted here.

[0011] Other features and advantages of example embodiments of the present disclosure will become apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

[0013] Figure 1A and Figure 1B is a schematic diagram illustrating an IAB network architecture in which example embodiments of the present disclosure may be implemented.

[0014] Figure 2 is a schematic diagram of inter-donor mobility of an IAB node according to an example embodiment of the present disclosure.

[0015] Figure 3 is a high-level message sequence chart illustrating the process of establishing an Xn connection according to an example embodiment of the present disclosure.

[0016] Figure 4 is a schematic message sequence chart illustrating a process of establishing an Xn connection between an IAB donor and a mobile central unit (m-CU) in an IAB node integration scenario according to an example embodiment of the present disclosure.

[0017] Figure 5 is a schematic message sequence chart illustrating an Xn connection setup procedure according to an example embodiment of the present disclosure.

[0018] Figure 6 is a schematic message sequence chart illustrating a process of establishing an Xn connection between an m-CU and a neighboring base station in an IAB node handover scenario according to an example embodiment of the present disclosure.

[0019] Figure 7 is a high-level message sequence chart illustrating the process of establishing an Xn connection according to an example embodiment of the present disclosure.

[0020] Figure 8 is a schematic message sequence chart illustrating a process of establishing an Xn connection initiated at an IAB donor according to an example embodiment of the present disclosure.

[0021] Fig. 9 is a schematic message sequence chart illustrating a process of establishing an Xn connection between an m-CU and a neighboring base station according to an example embodiment of the present disclosure.

[0022] Fig.10 is a schematic structural block diagram showing a device in a communication system in which an exemplary embodiment of the present disclosure may be implemented.

[0023] Throughout the drawings, the same or similar reference numerals indicate the same or similar elements, and repeated description of the same elements will be omitted. DETAILED DESCRIPTION

[0024] Hereinafter, some example embodiments are described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it is apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known circuits, techniques, and components are shown in block diagram form to avoid obscuring the concepts and features described.

[0025] As used herein, the term "network equipment" refers to any suitable equipment or entity that can provide a cell or coverage, through which a terminal device can access a network or receive a service. Network equipment can often be referred to as a base transceiver station (BTS), a base station (BS) or some other suitable dedicated for. The term "base station" or "base transceiver station" used herein may represent a node B (Node B or NB), an evolved node B (eNodeB or eNB), a next generation node B (gNB) or a next generation enhanced node B (ng-eNB). The base station may be implemented as a macro base station, a relay node or a low power node, such as a micro base station or a femto base station. The base station may also include or may be referred to as a RAN (radio access network) node, and may be composed of several distributed network units, such as a central unit (CU), one or more distributed units (DU), one or more remote radio heads (RRH) or remote radio units (RRU). The number and function of these distributed units depend on the selected split RAN architecture.

[0026] As used herein, the term "terminal device" or "user equipment" (UE) refers to any device or entity that can wirelessly communicate with network devices or with each other. Examples of terminal devices may include mobile phones, mobile terminals, mobile stations (MS), user stations, portable user stations, access terminals, personal digital assistants (PDAs), computers, wearable devices, vehicle-mounted communication devices, machine type communication (MTC) devices, D2D communication devices, V2X communication devices, sensors, etc. The term "terminal device" can be used interchangeably with UE, user terminal, mobile terminal, mobile station, or wireless device.

[0027] In a 5G communication network, a new radio (NR) cell can be deployed in different spectrum ranges, including a frequency range 1 (FR1) with an occupied frequency less than 6 GHz and a frequency range 2 (FR2) with an occupied frequency greater than 6 GHz. At higher frequencies, the coverage of the NR cell is relatively small. As a result, densification by deploying more and more base stations is one of the mechanisms that can be adopted to meet the increased capacity requirements while providing a full coverage area in a wireless network. In such a deployment, various forms of wireless connections using an integrated access and backhaul (IAB) node between a base station and a user equipment (UE) are supported in a 5G NR system. The IAB node can support wireless access and backhaul in both FR1 spectrum and FR2 spectrum. The NR UE can be transparently connected to the IAB node via NR. Further, in the case where the IAB node supports the backhaul of LTE access, the traditional long term evolution (LTE) UE can be transparently connected to the IAB node via LTE.

[0028] IAB nodes can be used in a variety of deployment scenarios, including support for outdoor small cell deployments, indoor deployments, or even vehicle-mounted relays (VMRs). For example, VMRs utilize mobile IAB nodes installed in vehicles (e.g., trains, buses, trailers, subways, etc.) to increase data rates and reliability for UEs in or around the vehicle.

[0029] In such a mobile deployment scenario, it may be desirable to support full migration of IAB nodes in order to have sufficient capabilities. For example, when a mobile IAB node deployed on a high-speed train with a UE wireless connection migrates from a source IAB donor base station to a target IAB donor base station, the communication and signaling interface with the source IAB donor needs to be completely released, and a new interface needs to be established for the target IAB donor base station.

[0030] Figure 1A FIG. 1 is a schematic diagram of an IAB network architecture with a single-hop backhaul in which an example embodiment of the present disclosure may be implemented. Figure 1A As shown in , the IAB node 110 may be connected to the core network 140 via the IAB donor 120, and the central unit 130 is provided for controlling one or more mobile IAB nodes including the IAB node 110. Hereinafter, the central unit 130 for controlling the mobile IAB node may be referred to as a mobile CU (m-CU). The m-CU 130 may be connected to a mobile IAB specific user plane function (UPF) 142, which may be referred to as a mobile UPF (m-UPF) hereinafter. Figure 1A The IAB network shown in may be part of a larger cellular communication system such as a 5G system (5GS).

[0031] The IAB donor 120 may be a radio access network (RAN) node, for example, a base station with backhaul connectivity to the core network 140. The IAB donor 120 may be viewed as a single logical node that includes a set of functions, such as a central unit (CU) 124, one or more distributed units (DU) 122, and potentially other functions. In some deployments, the IAB donor 120 may be separated according to these functions, which may all be collocated or non-collocated as allowed by the 3GPP NG-RAN architecture. Moreover, in the case where these functions do not perform IAB-specific tasks, some of the functions currently associated with the IAB donor 120 may be moved outside the donor. In an example deployment, the CU 124 may be deployed at a central office, and the DU 122 may be deployed at respective cell sites. In another example where the RAN has a cloud-based architecture, the CU 124 may be deployed in the cloud.

[0032] Donor CU 124 and donor DU 122 are connected via an F1 interface, and the operation of donor DU 122 may be partially controlled by donor CU 124. Figure 1A One donor DU 122 is shown in FIG. 1 , but any suitable number of DUs may be connected to the donor CU 124 of the IAB donor 120 . The donor DU 122 may serve one or more cells, and a cell may be supported by only one donor DU 122 .

[0033] In the context of 5G NR, the core network 140 may be a next generation core network (NGC). NGC 140 may include various entities and network functions (not shown), such as access and mobility management function (AMF), session management function (SMF), user plane function (UPF), non-3GPP interworking function (N3IWF), etc.

[0034] The IAB node 110 may maintain a distributed unit (DU) part 112 and a mobile termination (MT) part 114. The MT part 114 is a component of a mobile device that supplies functions residing on the IAB node 110, which terminates the radio interface layer of the backhaul Uu interface toward the corresponding DU 122 of the IAB donor 120. The MT 114 enables the IAB node 110 to act as a normal UE toward the IAB donor 120. For example, the MT 114 may select the best cell served by the donor DU 122 and establish a radio resource control (RRC) connection with the donor CU 124 in association with the donor DU 122.

[0035] The IAB DU 112 may host one or more transmit / receive points (TRPs) and serve one or more cells in the same manner as the donor DU 122. For example, the IAB DU cell may broadcast control signaling such as synchronization signal blocks (SSBs) and system information (SI). From the perspective of the UE, the IAB DU cell may be viewed as a normal cell such as a donor DU cell. The IAB DU 112 may have an F1 connection to the m-CU 130, and from the perspective of the NGC 140, the IAB DU 112 and the m-CU 130 may be viewed as base stations. The F1 connection and other backhaul connections may be carried via a PDU session established by accessing the RAN. During PDU session establishment, the NGC 140 may select an appropriate m-UPF 142, for example, in the same local edge cloud as the donor CU 124. The PDU session is used as a point-to-point link between the IAB MT 114 and the m-UPF 142 , and the bearer layer is configured for the PDU session between the IABMT 114 and the donor CU 124 .

[0036] The physical location of the m-CU 130 and the m-UPF 142 can be flexibly determined according to the network physical architecture. In one example, the m-CU 130 and the m-UPF 142 can reside on the IAB donor 120 as part of the function of the IAB donor 120. In another example where the access RAN has a cloud-based architecture, the m-CU 130 and the m-UPF 142 can be placed in a cloud infrastructure. Depending on the use case and range of movement of the mobile IAB node 110, the m-CU 130 and the m-UPF 142 can be placed in a RAN local cloud hosted by the IAB donor 120 or another donor node, for example. The advantage of the cloud-based architecture is that it can provide flexibility to serve a relatively large area with a dedicated mobile function serving the mobile IAB node 110. In some example embodiments, the m-CU 130 and the m-UPF 142 can be part of a specific slice serving the mobile IAB node.

[0037] In general, the mobile IAB network architecture shown reuses existing functions and interfaces defined in NR. In particular, the mobile IAB node 110 reuses the MT+DU structure of the current fixed IAB node, which can minimize changes to the IAB node hardware and software. IAB MT, IAB DU, donor DU, donor CU, UPF, AMF and SMF and corresponding interfaces NR Uu (between MT and IAB donor), F1, NG, X2 and N4 can be used as the baseline of the IAB architecture. Therefore, the mobile IAB architecture can serve traditional UEs with minimal or no impact on the access network. Enhancements to the IAB network can be implemented in dedicated functions or entities, namely m-CU 130, m-UPF 142 and mobile IAB node 110. The IAB node is almost transparent to the access RAN, which provides flexibility to apply architectures applied for various use cases and network deployment scenarios.

[0038] for Figure 1A The illustrated single-hop IAB network architecture carries the backhaul routing to the mobile IAB node 110 via a PDU session established between the IAB MT 114 and the m-UPF 142 through the access network RAN, and does not need to include a backhaul adaptation protocol (BAP) layer for the backhaul routing.

[0039] according to Figure 1AAnother advantage of the IAB network architecture shown in is that the RAN node that provides network access to the IAB node 110 can be an IAB-capable RAN node, such as an IAB donor 120, or a non-IAB-capable RAN node, such as a legacy gNB. It enables the IAB node 110 to connect to any NR RAN gNB, and operators do not need to upgrade a large number of legacy gNBs that normally do not need wireless backhaul for IAB support. This is particularly useful in scenarios where a mobile vehicle carrying the IAB node 110 travels a long distance and the IAB node 110 connects to many different gNBs deployed along the distance.

[0040] In an example embodiment, the mobile IAB node 110 may also be connected to the RAN node via one or more intermediate IAB nodes, where an example is shown in FIG. Figure 1B Reference Figure 1B , the mobile IAB node 110 may be connected to a static / fixed IAB node 118, which may be the last (most downstream) IAB node in a possible multi-hop chain service access UE. The IAB node 118 may include an IAB DU 117 and an IAB MT 119, the IAB DU 117 maintaining a Uu interface with an IAB MT 114 in the mobile IAB node 110, and the IAB MT 119 maintaining a Uu interface with an IAB donor DU 122 in an IAB donor 120. The IAB DU 117 may also have an F1 connection to an IAB donor CU 124 of the IAB donor 120, and the F1 connection may be carried via a PDU session or a backhaul adaptation protocol (BAP) layer (not shown).

[0041] Similar to Figure 1A In the architecture shown in FIG, the wireless backhaul of the mobile IAB node 110 is carried via the PDU session, and the radio bearer for the PDU session transparently passes through the static IAB node 118. Therefore, the mobile IAB node 110 is regarded as a normal UE connected to the static IAB node 118, and the BAP routing can be terminated at the access IAB node 118. Figure 1B Other aspects of the examples shown in Figure 1A The examples shown in are similar, and for convenience, repeated description is omitted here.

[0042] Figure 21 is a schematic diagram of the inter-donor mobility of an IAB node according to an embodiment of the present invention. A mobile IAB node 110 deployed on a vehicle (e.g., a bus, a train) can move with the vehicle. Initially, it can be assumed that the IAB node 110 is connected to a source donor 120 or a static IAB node (not shown) connected to the source donor 120. As the vehicle moves away from the source donor 120 toward the target donor 121, the quality of the wireless link between the IAB MT 114 and the source donor 120 or the static IAB node connected to the source donor 120 may deteriorate, and the quality of the wireless link between the IAB MT 114 and the target donor 121 or the static IAB node (not shown) connected to the target donor 121 may become better. When a certain threshold or condition is met, the IAB node 110 can migrate from the topology of the source donor 120 or the static IAB node connected to the source donor 120 to the topology of the target donor 121 or the static IAB node connected to the target donor 121.

[0043] By way of example, Figure 2 The migration of the IAB node 110 from the source donor 120 to the target donor 121 is shown. Similar to the source donor 120, the target donor 121 may also include a central unit (CU) 125 and one or more distributed units (DUs) 123. An Xn connection may be established between the source donor CU 124 and the target donor CU 125. For example, the Xn connection may be established by maintaining an updated list of neighboring cells. Automatic neighbor relation (ANR) updates / maintenance may be performed by utilizing UE measurement reports of detected cells. Once a new cell / gNB is detected, an Xn connection may be established between the CUs. The IAB MT 114 may change its access and backhaul connection to the target donor 121 during a normal handover process. Similarly, the CU user plane (UP) connection to the m-UPF 142 may be changed from the source donor CU 124 to the target donor CU 125 through a normal path switching process.

[0044] However, such a neighbor cell update process cannot be used between the donor CU 124 / 125 and the m-CU 130. The m-CU 130 can collect UE measurements from (multiple) IAB node cells, but these measurements are not related to the backhaul link between the IAB MT 114 and the donor. The m-CU 130 does not know which cells / nodes are candidates for handover of the IAB MT 114, and therefore which cells / nodes the m-CU 130 should establish Xn connections to. Because the F1 connection from the mobile IAB node 110 to the m-CU 130 is transparent to the access RAN, the m-CU 130 does not know which donor cell / node the IAB MT 114 is connected to or to which donor cell / node a handover has been performed.

[0045] Hereinafter, various example embodiments of the apparatus and method for Xn connection management will be described in detail with reference to the accompanying drawings. Example embodiments may be implemented to implement Xn establishment between a central unit capable of or dedicated to controlling a mobile IAB node (e.g., m-CU 130) and a RAN node (e.g., IAB donor 120 or non-IAB RAN node) that provides network access to the mobile IAB node. Example embodiments may also be implemented to implement Xn establishment between a central unit capable of or dedicated to controlling a mobile IAB node and one or more neighboring base stations (e.g., target donor 121) of the mobile IAB node, which may include a target base station for handover of the mobile IAB node. Example embodiments may support Xn connection establishment between a CU for controlling a mobile IAB node and a related RAN node, while having minimal impact on current F1AP and XnAP specifications. Although some example embodiments are described in the context of a 5G system, it should be understood that the various example embodiments described herein may also be applicable to systems other than 5G, such as a 6G system (6GS).

[0046] Figure 3 2 is a high-level message sequence chart illustrating a process 200 of establishing an Xn connection according to an example embodiment. The process may be performed by a mobile IAB node, a serving node supporting a serving cell to which the IAB node is connected, one or more neighboring base stations including, for example, an IAB target donor, and an m-CU for controlling the mobile IAB node. Figure 3 The operation shown. Figure 3 The IAB donor 120 is shown as an example of a serving node, although the serving node may also be a non-IAB RAN node, such as a traditional gNB or a static IAB node. The above network and terminal nodes may include a method for performing the following reference Figure 3 Multiple parts, modules, components or elements of the operations discussed. The parts, modules, components or elements may be implemented in various ways, including but not limited to software, hardware, firmware or any combination thereof.

[0047] refer to Figure 3At 210, IAB node 110 may establish an RRC connection between IAB node 110 and IAB donor 120. In some example embodiments, when IAB node 110 is powered on and initially registered with the network, IAB node 110 may establish an RRC connection between IAB node 110 and IAB donor 120 through a random access procedure. For example, IAB node 110 may detect a cell supported by IAB donor 120 as the best cell and initiate a random access procedure to the cell. In some other example embodiments, IAB node 110 may establish an RRC connection between IAB node 110 and IAB donor 120 during a handover process, by which IAB node 110 migrates from a previous IAB donor to a current IAB donor 120.

[0048] When the IAB node 110 initially connects to the network, the IAB node 110 may also establish an F1 connection to the m-CU 130 at operation 212. As discussed above with respect to FIG. 1 , the F1 connection is established between the distributed unit 112 and the m-CU 130, whose function is to control the IAB node 110. The F1 connection may be carried by a PDU session established through the IAB donor 120.

[0049] At 220, the IAB node 110 may transmit the cell information to the m-CU 130. At operation 212, during and / or after establishing the F1 connection, the cell information may be transmitted via an F1 application protocol (F1AP) message, and may include at least one of one or more neighboring cells and a serving cell for the IAB node 110. It should be understood that in the case of carrier aggregation (CA), the IAB node 110 may have multiple serving cells including a primary cell and one or more secondary cells. Since the multiple serving cells are operated by one base station (e.g., the IAB donor 120), the cell information may indicate any one of the multiple serving cells of the IAB node 110. The one or more neighboring cells may be supported by one or more neighboring base stations 150.

[0050] In an example embodiment, after the IAB node 110 is connected to the network, the IAB node 110 may transmit the serving cell information to the m-CU 130 .

[0051] In an example embodiment, when the IAB node 110 sends a measurement report to the IAB donor 120, the IAB node 110 may transmit information of one or more neighboring cells to the m-CU 130. The one or more neighboring cells may be indicated as candidate target cells in the measurement report. Alternatively or additionally, when the one or more neighboring cells have a signal level above a certain threshold (which indicates that the one or more neighboring cells are potential handover candidates for the IAB node 110), the IAB node 110 may transmit information of the one or more neighboring cells to the m-CU 130.

[0052] At 230 , when m-CU 130 receives the cell information, m-CU 130 may initiate an Xn setup procedure to establish an Xn connection between m-CU 130 and one or more base stations supporting the cells indicated in the received cell information.

[0053] like Figure 3 As shown, when the received cell information indicates a serving cell served by the IAB donor 120 (or by the IAB node 118 connected to the IAB donor 120), the m-CU 130 may establish an Xn connection between the m-CU 130 and the IAB donor 120, which is indicated in the serving cell information. Alternatively or additionally, when the received cell information indicates one or more neighboring cells, the m-CU 130 may establish an Xn connection between the m-CU 130 and one or more neighboring base stations 150 supporting the one or more neighboring cells.

[0054] Figure 4 3 is a schematic message sequence diagram illustrating a process 300 for establishing an Xn connection between an IAB donor 120 and an m-CU 130 in an IAB node integration scenario according to an example embodiment of the present disclosure. It should be understood that Figure 4 The operations shown in the above reference Figure 3 A specific example of the process 200 is discussed and may be incorporated into Figure 3 in the process shown in .

[0055] refer to Figure 4 At 310, the IAB MT component 114 of the IAB node 110 may establish a radio resource control (RRC) connection with the donor CU 124 of the IAB donor 120. As discussed above, the IAB MT 114 may establish the RRC connection to the donor CU 124 via a random access procedure or a handover procedure. With the IAB network architecture as shown in FIG. 1 , the IAB MT 114 may be connected to the donor CU 124 regardless of whether the IAB donor 120 supports IAB.

[0056] In an example embodiment, for the backhaul connection of the IAB node 110, at 310, the IAB MT 114 may also establish a PDU session to the m-UPF 142 (FIG. 1). During the initial RRC connection setup, the IAB MT 114 may indicate to the network that the IAB node 110 is a mobile IAB node, and the NGC 140 may select a central unit capable of or dedicated to controlling mobile IAB nodes, and select a mobile IAB-specific user plane function (UPF) for the IAB node 110. For example, an access and mobility management function (AMF) in the NGC 140 may have information about the m-CU near the IAB node 110, and it may select the m-CU 130 for the IAB node 110. The service management function (SMF) in the NGC 140 may select the m-UPF 142 in the same local edge cloud as the donor CU 124 for the IAB MT 114. The PDU session between the IAB MT 114 and the m-UPF 142 may be used as a transport layer for an F1 interface to be established between the IAB DU 112 and the m-CU 130, which will be described in more detail below.

[0057] In another example embodiment, the IAB node 110 may receive information of the m-CU 130 from an operations administration and maintenance (OAM) server (not shown). For example, the IAB MT 114 may establish a PDU session with the OAM server, indicate the serving cell information to the OAM server, and obtain configuration information on the m-CU 130. The configuration information of the m-CU 130 may include, for example, transport network layer (TNL) association information. In another example, the IAB DU 112 may be pre-configured by the OAM server regarding the m-CU information (e.g., TNL association information). This may be applicable to a scenario where, for example, the m-CU 130 covers a moving area of ​​the mobile IAB node 110. The TNL association information may include, for example, a tunnel endpoint identifier (TEID), a transport layer address, and optionally other information for setting up an F1 connection.

[0058] At 320, the IAB MT 114 may transmit the serving cell information to the IAB DU 112 of the IAB node 110. In an example, the serving cell information may include, for example, a physical cell ID (PCI), a cell global ID (CGI), a tracking area code (TAC), frequency information, and other information of the serving cell.

[0059] At 330, the IAB DU 112 of the IAB node 110 may establish an F1 connection / interface to the m-CU 130. As discussed above, information of the m-CU 130 may be acquired during the connection setup process at operation 310. The F1 interface may be used to exchange application layer data between the IAB DU 112 and the m-CU 130. In an example embodiment, operation 330 may include a step 332 of sending an F1 SETUP REQUEST message from the IAB DU 112 to the m-CU 130. The message may be transparently transmitted to the m-CU 130 via a PDU session established between the IAB MT 114 and the m-UPF 142 by accessing the RAN.

[0060] The F1 SETUP REQUEST message may include an ID of the IAB DU 112 and information of one or more cells served by the IAB DU 112. For example, the F1 SETUP REQUEST may include an information element "served cell information". In an example embodiment, the F1 SETUP REQUEST message may also include serving cell information received at 320 indicating serving cells supported by the donor DU 124 to which the IAB node 110 is connected. For example, the F1 SETUP REQUEST message may be extended with a new information element (IE) "neighbor cell information" which refers to the serving cell of the donor DU 122 to which the IAB MT 114 is connected. The "neighbor cell information" IE may reuse an IE in the 3GPP F1AP or XnAP specification, and it will minimize the impact on the existing specification.

[0061] At 334 , in response to receiving the F1 SETUP REQUEST message, the m-CU 130 may transmit an F1 SETUP RESPONSE message to the IAB DU 112 .

[0062] When the F1 setup procedure is complete, the F1 interface is operational and other F1AP messages may be exchanged between the IAB DU 112 and the m-CU 130. In an example embodiment, instead of using the F1 SETUP RESPONSE message, the IAB DU 112 may transmit the serving cell information to the m-CU 130 via another F1AP message after setting up the F1 connection. For example, at 340, the serving cell information may be transmitted to the m-CU 130 in the gNB-DU configuration update procedure.

[0063] like Figure 4 As shown, at 342, the IAB DU 112 may send a gNB-DU configuration update (GNB-DUCONFIGURATION UPDATE) message to the m-CU 130, which may be extended with an IE "neighbor cellinformation" including the serving cell information. At 344, the m-CU 130 may respond to the IAB DU 112 with a gNB-DU configuration update confirmation (GNB-DUGNB-DUCONFIGURATION UPDATE ACKNOWLEDGE) message to confirm the successful reception of the serving cell information.

[0064] At 350, the m-CU 130 may establish an Xn connection between the m-CU 130 and the IAB donor 120 supporting the serving cell using the serving cell information provided by the IAB DU 112 of the IAB node 110. In an example embodiment, the m-CU 130 may reuse a conventional Xn setup procedure at 350.

[0065] exist Figure 4 In the illustrated example embodiment, the IAB node 110 sends the serving cell information to the m-CU 130, and then the m-CU 130 initiates an Xn connection setup procedure to establish an Xn connection between the m-CU 130 and the IAB donor 120 supporting the serving cell.

[0066] In an example embodiment, at 350, during or after the Xn setup process, the m-CU 130 may also receive neighboring cell information of the IAB node 110 from the IAB donor 120, and establish an Xn connection between the m-CU 130 and one or more neighboring base stations, as shown in FIG. Figure 5 was displayed in.

[0067] refer to Figure 5At 351, for example, in response to receiving the serving cell information from the IAB DU 112, the m-CU 130 may send an XN SETUP REQUEST message to the IAB donor 120. Then at 352, the IAB donor 120 may respond to the m-CU 130 with an XN SETUP RESPONSE message. In an example embodiment, the XN SETUP RESPONSE message may be extended with a "neighbor cell information" IE, which refers to one or more neighboring cells for the IAB node 110. The IAB donor 120 may receive the neighboring cell information from the IAB MT 114, for example, via a measurement report. In an example embodiment, the IAB donor 120 may maintain a neighboring cell list for the IAB node 110, for example, through an automatic neighbor relation (ANR) procedure.

[0068] When the Xn setup procedure is complete, an Xn interface is established between the IAB donor 120 and the m-CU 130, and other messages may be transmitted over the Xn interface. In an example embodiment, instead of using an XN SETUP RESPONSE message, the IAB donor 120 may utilize an NG-RAN node configuration update procedure to transmit neighboring cell information to the m-CU 130. For example, at 353, the IAB donor 120 may send an NG-RAN NODE CONFIGURATION UPDATE message to the m-CU 130. The NG-RAN NODE CONFIGURATION UPDATE message may be extended with a "neighbor cell information" IE, which refers to one or more neighboring cells for the IAB node 110. At 354, the m-CU 130 may respond to the IAB donor 120 with an NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE message to confirm that it has successfully received the neighboring cell information.

[0069] At 352 or 354, in response to the neighboring cell information received from the IAB donor 120, the m-CU 130 may establish an Xn connection between the m-CU 130 and one or more neighboring base stations supporting the neighboring cells. For example, at 362, the m-CU 130 may send an XN SETUP REQUEST message to the neighboring base station 150. At 364, the neighboring base station 150 may send an XN SETUP RESPONSE message to the m-CU 130 to complete the Xn setup process.

[0070] Figure 6 is a schematic message sequence chart illustrating a process of establishing an Xn connection between an m-CU and one or more neighboring base stations in an IAB node handover scenario according to an example embodiment of the present disclosure.

[0071] refer to Figure 6 At 410, the MT 114 of the IAB node 110 may establish an RRC connection to the donor CU 124 of the IAB donor 120. Further, at 420, the IAB DU 112 of the IAB node 110 may establish an F1 connection to the m-CU 130. The details of operations 410 and 420 may be referred to above regarding Figure 4 Operation 310 and operation 330 are discussed, and repeated descriptions thereof are omitted here.

[0072] At 430, the IAB MT 114 may indicate to the IAB DU 112 one or more neighboring cells detected at the IAB MT 114. The IAB MT 114 may indicate the neighboring cells to the IAB DU 112 when the IAB MT 114 transmits a measurement report (e.g., a measurement report triggered by mobility event A3 or A4) to the IAB donor 120, or when the neighboring cells have a signal level above a certain threshold. When the IAB donor 120 receives the measurement report from the IAB node 110, the IAB donor 120 may decide to hand over the IAB node 110 to a target cell, e.g., a best cell among the neighboring cells. A conventional inter-CU handover procedure may be performed to move the access and backhaul connection of the IAB node 110 from the source donor 120 to the target donor, as described above with respect to Figure 2 discussed.

[0073] In response to receiving the neighboring cell information at 430, at 440, the IAB DU 112 of the IAB node 110 may transmit the neighboring cell information to the m-CU 130. In an example embodiment, the neighboring cell information may be transmitted in a gNB-DU configuration update procedure. For example, the IAB DU 112 may send a GNB-DU CONFIGURATION UPDATE message to the m-CU 130, which may be extended with a "neighbor cell information" IE that references the neighboring cell.

[0074] At 450, using the neighboring cell information received from the IAB DU 112 of the IAB node 110, the m-CU 130 can establish an Xn connection between the m-CU 130 and one or more neighboring base stations 150 supporting the neighboring cells. In an example embodiment, the Xn setup process can be performed before the handover process or in parallel with the handover process. Since the handover target cell is included in the neighboring cell information, at 450, the Xn connection can be established between the m-CU 130 and the handover target base station in a timely manner without violating the mobility requirements of the IAB node. Figure 5 Operation 362 and operation 364 in hereinafter describe the details of operation 450, and a repeated description thereof is omitted here.

[0075] Figure 7 is a high-level message sequence chart illustrating a process 500 for establishing an Xn connection according to an example embodiment of the present disclosure. Figures 3 to 6 Unlike the process shown in , in process 500, the Xn setup process may be initiated at a RAN node such as the IAB donor 120 or a non-IAB capable base station.

[0076] refer to Figure 7 At 510, the IAB node 110 may establish an RRC connection to the IAB donor 120. When the IAB node 110 is connected to the IAB donor 120, at 512, the IAB node 110 may also establish an F1 connection to the m-CU 130 via the access RAN. The details of the RRC connection setup procedure and the F1 connection setup procedure have been discussed above, and a repeated description thereof is omitted here.

[0077] At 520, the IAB node 110 may transmit the cell information to the IAB donor 120. In an example embodiment, the cell information may include cells served by the IAB DU 112 in the IAB node 110, hereinafter referred to as "IAB DU cells". Figure 1B In the case of being connected to the static IAB node 118 as shown in FIG. 8 , the IAB node 110 may transmit the cell information to the static IAB node 118 , and the static IAB node 118 may send the cell information to the IAB donor 120 .

[0078] On the side of the IAB donor 120, at 530, the IAB donor 120 may establish an Xn connection between the IAB donor 120 and the m-CU 130 in association with the IAB DU 112 serving the IAB DU cell. At 540, the IAB donor 120 may also transmit neighboring cell information to the m-CU 130. The neighboring cell information may indicate one or more neighboring cells for the IAB node 110, including, for example, neighboring cells supported by the IAB donor 120 and neighboring cells supported by neighboring base stations, which would be primary target cell candidates for the IAB node 110 when, for example, the IAB node 110 is moving away from the coverage of the IAB donor 120. In an example embodiment, the IAB donor 120 may maintain a neighboring cell list for the IAB node 110 based on a measurement report received from the IAB node 110.

[0079] On the m-CU 130 side, in response to receiving the neighboring cell information from the IAB donor 120, the m-CU 130 may establish an Xn connection between the m-CU 130 and one or more neighboring base stations 150 supporting the neighboring cells indicated in the received neighboring cell information.

[0080] Figure 8 6 is a schematic message sequence diagram illustrating a process 600 of establishing an Xn connection initiated at the IAB donor 120 according to an example embodiment of the present disclosure. It should be understood that Figure 8 The operations shown represent the above reference Figure 7 Specific examples of the process 500 discussed and may be incorporated into Figure 7 in the process shown in .

[0081] Reference Figure 8 At 610, the IAB MT component 114 of the IAB node 110 may establish a radio resource control (RRC) connection with the donor CU 124 in association with the donor DU 122 in the IAB donor 120. During a cell selection / reselection process before establishing the RRC connection to the cell at 610, the IAB MT 114 may receive system information (SI) broadcasted by the donor DU 122 of the IAB donor 120. In an example embodiment, the SI may include an indication idleModeMeasurementsNR in a system information block 1 (SIB1) to indicate that the IAB donor 120 supports idle mode measurements. If the indication is received, the IAB MT 114 may include an indication idleMeasAvailable in the RRC setup complete message to indicate that idle mode measurement reports are available at the IAB MT 114.

[0082] When the RRC connection is established between the IAB MT 114 and the IAB donor CU 124, the IAB node 110 may also establish an F1 connection between the IAB DU 112 and the m-CU 130 at 612. Details of the RRC connection setup procedure and the F1 connection setup procedure have been discussed above, and a repeated description thereof is omitted here.

[0083] At 620, the IAB DU 112 may transmit the cell information to the IAB MT 114 of the IAB node 110. The cell information may include one or more cells served by the IAB DU 112. In half-duplex mode, the IAB MT 114 cannot detect the cell(s) served by the IAB DU 112, and the cell information is provided from the IAB DU 112 to the IAB MT 114.

[0084] At 630, the IAB MT 114 may transmit the cell information of the IAB DU cell to the donor CU 124 of the IAB donor 120. In an example embodiment, when the IAB MT 114 indicates idleMeasAvailable in the RRC Setup Complete message to the donor CU 124, the donor CU 124 may request the IAB DU cell information through a UE information request message UEInformationRequest including an idleModeMeasurementReq IE. The IAB MT 114 may then transmit the IAB DU cell information to the IAB CU 124 in a response message UEInformationResponse as an idle mode measurement report. Because the IAB MT 114 cannot measure the IAB-DU cell (with a half-duplex assumption), the measurement result in the response message may have a dummy value suitable for the donor CU 124 to identify the IAB DU cell but insufficient to trigger an immediate handover of the IAB MT 114 to its collocated DU cell. In an example, the cell information may also indicate an identifier of a base station, ie, the m-CU 130 supports an IAB DU cell.

[0085] At 642, based on the received IAB DU cell information, the IAB donor CU 124 may initiate an Xn setup procedure by sending an XN SETUP REQUEST message to the m-CU 130. In an example embodiment, the XN SETUP REQUEST message may include neighbor cell information indicating one or more neighbor cells for the IAB node 110. The donor CU 124 may obtain the neighbor cell information from a measurement report received from the IAB node 110. In an example embodiment, the donor CU 124 may maintain a neighbor cell list for the IAB node 110 through automatic neighbor relation (ANR). The XN SETUP REQUEST message may be extended with a "neighbor cell information" IE that references the neighbor cells of the IAB node 110.

[0086] Then, at 644, the m-CU 130 may reply with an XN SETUP RESPONSE message to complete the Xn setup process.

[0087] When the Xn setup process is complete, an Xn interface is established between the donor CU 124 of the IAB donor 120 and the m-CU 130, and additional Xn application protocol (XnAP) messages may be transmitted via the Xn interface. In an example embodiment, instead of using an XNSETUP REQUEST message, at 646, the donor CU 124 may send an NG-RAN NODECONFIGURATION UPDATE message to the m-CU 130, which may be extended with a "neighbor cell information" IE that references neighbor cells for the IAB node 110. At 648, the m-CU 130 may respond to the donor CU 124 with an NG-RAN NODECONFIGURATION UPDATE ACKNOWLEDGE message to confirm that it has successfully received the neighbor cell information.

[0088] At 650 , using the neighboring cell information received from the donor CU 124 , the m-CU 130 may establish an Xn connection between the m-CU 130 and one or more neighboring base stations 150 supporting one or more neighboring cells indicated in the neighboring cell information received at operation 642 or operation 646 .

[0089] Fig. 9 7 is a schematic message sequence diagram illustrating a process 700 of establishing an Xn connection between an m-CU 130 and one or more neighboring base stations 150 according to an example embodiment of the present disclosure. It should be understood that the process 700 may also be applied to Figure 3 , Figures 5 to 8In order to establish an Xn connection between the m-CU 130 and the neighboring base station 150.

[0090] refer to Fig. 9 At 710, the m-CU 130 may establish an Xn connection with a neighboring base station 150 of a neighboring cell serving the IAB node 110 in a standby state. The standby Xn connection cannot be used to transmit XnAP messages between the m-CU 130 and the neighboring base station 150.

[0091] At 720, the m-CU 130 may activate one or more of the standby Xn connections. For example, when the IAB donor 120 decides to switch the IAB node 110 to a neighboring cell served by a neighboring base station (inter-CU handover), the IAB donor 120 may, for example, notify the m-CU 130 of the target neighboring cell via an operable Xn connection between the IAB donor 120 and the m-CU 130, and then the m-CU 130 may activate a standby Xn connection between the m-CU 130 and the target neighboring base station serving the target neighboring cell. In the case of conditional handover, the m-CU 130 may activate multiple standby Xn connections to multiple potential target base stations. Other standby Xn connections may remain in a standby state or may be released.

[0092] In process 700, m-CU 130 may establish a backup Xn connection to a certain number of neighboring base stations of IAB node 110. When IAB donor 120 decides to switch a target base station or multiple potential target base stations, IAB donor 120 may notify m-CU 130 of the target base station or potential target base stations, and then m-CU 130 may activate the Xn connection to the target base station or each potential target base station. Using process 700, when a handover or conditional handover occurs, m-CU 130 may quickly establish an operational Xn connection with the target base station or potential target base station because a backup Xn connection has been established before the handover is triggered. Therefore, process 700 may minimize the delay caused by the Xn setup process and meet IAB-MT mobility requirements.

[0093] Fig.10 8 is a schematic block diagram showing a device in a communication system 800 in which an exemplary embodiment of the present disclosure can be implemented. Fig.10 As shown, the communication system 800 may include a first network device 810 that may be implemented as the IAB node 110 discussed above, a second network device 820 that may be implemented as the IAB donor 120 discussed above, and a third network device 830 that may be implemented as the m-CU 130 discussed above.

[0094] refer to Fig.10, the first network device 810 may include one or more processors 812, one or more memories 814, and one or more transceivers (not shown) interconnected by one or more buses. The one or more buses may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, optical fiber, optical device, or other optical communication device. Each of the one or more transceivers may include a receiver and a transmitter connected to one or more antennas. The first network device 810 may communicate wirelessly with the second network device 820 via one or more antennas. The one or more memories 814 may include a computer program code 816. The one or more memories 814 and the computer program code 816 may be configured to, when executed by the one or more processors 812, cause the first network device 810 to perform the processes and steps associated with the IAB node 110 as discussed above.

[0095] The second network device 820 may include one or more processors 822, one or more memories 824, one or more transceivers (not shown), and one or more network interfaces (not shown) interconnected by one or more buses. One or more buses may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, optical fiber, optical device, or other optical communication device. Each of the one or more transceivers may include a receiver and a transmitter connected to one or more antennas. The second network device 820 may communicate wirelessly with the first network device 810 via one or more antennas. One or more network interfaces may provide wired or wireless communication links, and the second network device 820 may communicate with other network devices, entities, elements, or functions via wired or wireless communication links. For example, the second network device 820 may communicate with the third network device 830 via an Xn interface. One or more memories 824 may include a computer program code 826. One or more memories 824 and computer program code 826 may be configured to, when executed by one or more processors 822, cause the second network device 820 to perform the processes and steps associated with the IAB donor 120 as described above.

[0096] The third network device 830 may include one or more processors 832, one or more memories 834, and one or more network interfaces (not shown) interconnected by one or more buses. One or more buses may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, optical fiber, optical device, or other optical communication device. One or more network interfaces may provide a wired or wireless communication link, through which the third network device 830 may communicate with other network devices, entities, elements, or functions. For example, the third network device 830 may communicate with the first network device 810 on the F1 interface and communicate with the second network device 820 via the Xn interface. One or more memories 834 may include a computer program code 836. One or more memories 834 and computer program code 836 may be configured to, when executed by one or more processors 832, cause the third network device 830 to perform processes and steps related to the m-CU130 as described above.

[0097] The one or more processors 812, 822, and 832 discussed above may be any suitable type suitable for the local technology network, and may include a general purpose processor, a special purpose processor, a microprocessor, a digital signal processor (DSP), one or more processors in a processor-based multi-core processor architecture, and one or more processors in special purpose processors such as those developed based on field programmable gate arrays (FPGAs) and application specific integrated circuits (ASICs). The one or more processors 812, 822, and 832 may be configured to control other elements of the network device / network node and operate in cooperation with them to implement the processes discussed above.

[0098] One or more memories 814, 824, and 834 may include at least one storage medium in various forms, such as volatile memory and / or non-volatile memory. Volatile memory may include, but is not limited to, for example, random access memory (RAM) or cache. Non-volatile memory may include, but is not limited to, for example, read-only memory (ROM), hard disk, flash memory, etc. Further, one or more memories 814, 824, and 834 may include, but are not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any combination thereof.

[0099] It should be understood that the blocks in the drawings can be implemented in various ways, including software, hardware, firmware, or any combination thereof. In some embodiments, one or more blocks can be implemented using software and / or firmware (e.g., machine executable instructions stored in a storage medium). In addition to or in place of machine executable instructions, some or all of the blocks in the drawings can be implemented at least in part by one or more hardware logic components. For example, but not limited to, illustrative types of hardware logic components that can be used include field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0100] Some example embodiments also provide computer program codes or instructions that can cause a device or apparatus to perform a process as described above when executed by one or more processors. The computer program code for executing the process of the example embodiments can be written in any combination of one or more programming languages. The computer program code can be provided to one or more processors or controllers of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that the program code enables the functions / operations specified in the flow chart and / or block diagram to be implemented when executed by the processor or controller. The program code can be executed entirely on the machine, partially on the machine, as a separate software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0101] Some example embodiments also provide a computer program product or computer readable medium in which a computer program code or instruction is stored. A computer readable medium may be any tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or apparatus. A machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. A more specific example of a machine readable storage medium would include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0102] Further, although the operation is depicted in a particular order, this should not be understood as requiring to perform such operation in the particular order shown or in the order of sequence, or to perform all the operations shown to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these details should not be interpreted as limiting the scope of the present disclosure, but should be interpreted as a description of the possible specific features of a particular embodiment. Some of the features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0103] Although the subject matter has been described in language specific to structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as examples of implementing the claims.

Claims

1. An integrated access and backhaul node, comprising: at least one processor; as well as at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the integrated access and backhaul node to at least: establishing a first connection between a mobile terminating component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as During and / or after establishing the second connection, cell information is transmitted to the central unit, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node.

2. The integrated access and backhaul node of claim 1, wherein the mobile terminating component sends the cell information to the distributed unit, and the distributed unit transmits the cell information to the central unit.

3. An integrated access and backhaul node according to claim 1, wherein the first connection between the mobile termination component in the integrated access and backhaul node and the serving node is established during a radio resource control connection setup procedure or during a handover procedure, and the second connection between the distributed unit in the integrated access and backhaul node and the central unit is partially carried via the first connection.

4. The integrated access and backhaul node according to claim 3, wherein the integrated access and backhaul node is pre-configured with the information of the central unit by an operation management and maintenance server, or the integrated access and backhaul node receives the information of the central unit from the operation management and maintenance server.

5. The integrated access and backhaul node according to claim 3, wherein the integrated access and backhaul node receives the information of the central unit from an access and mobility management function server.

6. The integrated access and backhaul node of claim 1 , wherein the integrated access and backhaul node transmits the cell information of the one or more neighboring cells in the following cases: The integrated access and backhaul node transmits a measurement report to the serving node; and / or The one or more neighboring cells have a signal level above a threshold.

7. The integrated access and backhaul node of claim 1, wherein the serving node is an integrated access and backhaul donor node, a non-integrated access and backhaul radio access network node, or a static integrated access and backhaul node.

8. A central unit for controlling one or more integrated access and backhaul nodes, comprising: at least one processor; as well as at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the central unit to at least: establishing a second connection between a distributed unit in an integrated access and backhaul node and the central unit; receiving, during and / or after establishing the second connection, cell information from the integrated access and backhaul node, the cell information indicating at least one of one or more neighboring cells and serving cells for the integrated access and backhaul node; as well as A third connection is established between the central unit and one or more base stations serving the at least one of the one or more neighboring cells and the serving cell.

9. The central unit according to claim 8, wherein the cell information received from the integrated access and backhaul node indicates the serving cell of the integrated access and backhaul node, and The at least one memory and the computer program code are further configured to, with the at least one processor, cause the central unit to at least: receiving, during and / or after establishing the third connection between the central unit and the serving base station, neighboring cell information from a serving base station supporting the serving cell, the neighboring cell information indicating one or more neighboring cells for the integrated access and backhaul node; and A third connection is established between the central unit and one or more neighboring base stations supporting the one or more neighboring cells.

10. An integrated access and backhaul node, comprising: at least one processor; as well as at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the integrated access and backhaul node to at least: establishing a first connection between a mobile terminating component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as Transmitting cell information to the serving node, the cell information indicating a cell served by the distributed unit in the integrated access and backhaul node.

11. The integrated access and backhaul node of claim 10, wherein the serving node is an integrated access and backhaul donor node, a non-integrated access and backhaul radio access network node, or a static integrated access and backhaul node.

12. A radio access network node, comprising: at least one processor; as well as at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the radio access network node to at least: receiving cell information from a mobile terminating component in an integrated access and backhaul node, the cell information indicating cells served by a distributed unit in the integrated access and backhaul node; as well as Based on the received cell information, a third connection is established between the radio access network node and a central unit for controlling the integrated access and backhaul node, the central unit having a second connection with the distributed unit in the integrated access and backhaul node.

13. The radio access network node according to claim 12, wherein the radio access network node is an integrated access and backhaul donor node or a non-integrated access and backhaul radio access network node.

14. The radio access network node of claim 12, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the radio access network node to at least: During and / or after establishing the third connection between the radio access network node and the central unit, transmitting neighboring cell information to the central unit for controlling the integrated access and backhaul node, the neighboring cell information indicating one or more neighboring cells for the integrated access and backhaul node.

15. A central unit for controlling one or more integrated access and backhaul nodes, comprising: at least one processor; as well as at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the central unit to at least: establishing a third connection between the central unit and a radio access network node; receiving, during and / or after establishing the third connection between the central unit and the radio access network node, neighboring cell information from the radio access network node, the neighboring cell information indicating one or more neighboring cells for an integrated access and backhaul node under control of the central unit; as well as A third connection is established between the central unit and one or more neighboring base stations, the one or more neighboring base stations supporting the one or more neighboring cells indicated in the neighboring cell information.

16. The central unit according to claim 15, wherein the radio access network node is an integrated access and backhaul donor node or a non-integrated access and backhaul radio access network node, the non-integrated access and backhaul radio access network node providing network access to the integrated access and backhaul node.

17. A method implemented at an integrated access and backhaul node, comprising: establishing a first connection between a mobile terminating component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as During and / or after establishing the second connection, cell information is transmitted to the central unit, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node.

18. The method of claim 17, wherein the mobile terminating component sends the cell information to the distributed unit, and the distributed unit transmits the cell information to the central unit.

19. The method of claim 17, wherein the first connection between the mobile terminating component in the integrated access and backhaul node and the serving node is established during a radio resource control connection setup procedure or during a handover procedure, and the second connection between the distributed unit in the integrated access and backhaul node and the central unit is partially carried via the first connection.

20. The method of claim 19, wherein the integrated access and backhaul node is preconfigured with the information of the central unit by an operation management and maintenance server, or the integrated access and backhaul node receives the information of the central unit from an operation management and maintenance server.

21. The method of claim 19, wherein the integrated access and backhaul node receives the information of the central unit from an access and mobility management function server.

22. The method of claim 17, wherein the integrated access and backhaul node transmits the cell information of the one or more neighboring cells in the following circumstances: The integrated access and backhaul node transmits a measurement report to the serving node; and / or The one or more neighboring cells have a signal level above a threshold.

23. The method of claim 17, wherein the serving node is an integrated access and backhaul donor node, a non-integrated access and backhaul radio access network node, or a static integrated access and backhaul node.

24. A method implemented at a central unit for controlling one or more integrated access and backhaul nodes, comprising: establishing a second connection between a distributed unit in an integrated access and backhaul node and the central unit; receiving, during and / or after establishing the second connection, cell information from the integrated access and backhaul node, the cell information indicating at least one of one or more neighboring cells and serving cells for the integrated access and backhaul node; as well as A third connection is established between the central unit and one or more base stations serving the at least one of the one or more neighboring cells and the serving cell.

25. The method of claim 24, wherein the cell information received from the integrated access and backhaul node indicates the serving cell of the integrated access and backhaul node, and The method further comprises: receiving, during and / or after establishing the third connection between the central unit and the serving base station, neighboring cell information from a serving base station supporting the serving cell, the neighboring cell information indicating one or more neighboring cells of the integrated access and backhaul node; as well as A third connection is established between the central unit and one or more neighboring base stations supporting the one or more neighboring cells.

26. A method implemented at an integrated access and backhaul node, comprising: establishing a first connection between a mobile terminating component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as Transmitting cell information to the serving node, the cell information indicating a cell served by the distributed unit in the integrated access and backhaul node.

27. The method of claim 26, wherein the serving node is an integrated access and backhaul donor node, a non-integrated access and backhaul radio access network node, or a static integrated access and backhaul node.

28. A method implemented at a radio access network node, comprising: receiving cell information from a mobile terminating component in an integrated access and backhaul node, the cell information indicating cells served by a distributed unit in the integrated access and backhaul node; as well as Based on the received cell information, a third connection is established between the radio access network node and a central unit for controlling the integrated access and backhaul node, the central unit having a second connection with the distributed unit in the integrated access and backhaul node.

29. The method of claim 28, wherein the radio access network node is an integrated access and backhaul donor node or a non-integrated access and backhaul radio access network node.

30. The method of claim 28, further comprising: During and / or after establishing the third connection between the radio access network node and the central unit, transmitting neighboring cell information to the central unit for controlling the integrated access and backhaul node, the neighboring cell information indicating one or more neighboring cells for the integrated access and backhaul node.

31. A method implemented at a central unit controlling one or more integrated access and backhaul nodes, comprising: establishing a third connection between the central unit and a radio access network node; receiving, during and / or after establishing the third connection between the central unit and the radio access network node, neighboring cell information from the radio access network node, the neighboring cell information indicating one or more neighboring cells for an integrated access and backhaul node under control of the central unit; as well as A third connection is established between the central unit and one or more neighboring base stations, the one or more neighboring base stations supporting the one or more neighboring cells indicated in the neighboring cell information.

32. The method of claim 31 , wherein the radio access network node is an integrated access and backhaul donor node or a non-integrated access and backhaul radio access network node, the non-integrated access and backhaul radio access network node providing network access to the integrated access and backhaul node.

33. An apparatus comprising: means for establishing a first connection between a mobile terminating component in an integrated access and backhaul node and a cell served by a serving node; means for establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as Means for transmitting cell information from the integrated access and backhaul node to the central unit during and / or after establishing the second connection, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node.

34. An apparatus comprising: means for establishing a second connection between a distributed unit in an integrated access and backhaul node and a central unit for controlling said integrated access and backhaul node; means for receiving, at a central unit, cell information from the integrated access and backhaul node during and / or after establishing the second connection, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node; as well as Means for establishing a third connection between the central unit and one or more base stations serving the at least one of the one or more neighboring cells and the serving cell.

35. An apparatus comprising: means for establishing a first connection between a mobile terminating component in an integrated access and backhaul node and a cell served by a serving node; means for establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as Means for transmitting cell information from the integrated access and backhaul node to the serving node, the cell information indicating cells served by the distributed unit in the integrated access and backhaul node.

36. An apparatus comprising: means for receiving, at a radio access network node, cell information from an integrated access and backhaul node, the cell information indicating cells served by a distributed unit in the integrated access and backhaul node; as well as Means for establishing a third connection between the radio access network node and a central unit for controlling the integrated access and backhaul node based on the received cell information, the central unit having a second connection with the distributed unit in the integrated access and backhaul node.

37. An apparatus comprising: means for establishing a third connection between a central unit for controlling one or more integrated access and backhaul nodes and a radio access network node; means for receiving, at a central unit, from the radio access network node, neighboring cell information during and / or after establishment of the third connection between the central unit and the radio access network node, the neighboring cell information indicating one or more neighboring cells for an integrated access and backhaul node under control of the central unit; as well as Means for establishing a third connection between the central unit and one or more neighboring base stations, the one or more neighboring base stations supporting the one or more neighboring cells indicated in the neighboring cell information.

38. A computer program product embodied in at least one computer-readable medium and comprising instructions that, when executed by at least one processor of an integrated access and backhaul node, cause the integrated access and backhaul node to at least: establishing a first connection between a mobile terminating component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as During and / or after establishing the second connection, cell information is transmitted from the integrated access and backhaul node to the central unit, the cell information indicating at least one of one or more neighboring cells and a serving cell for the integrated access and backhaul node.

39. A computer program product, embodied in at least one computer readable medium and comprising instructions which, when executed by at least one processor of a central unit, cause the central unit to at least: establishing a second connection between the central unit and a distributed unit in an integrated access and backhaul node controlled by the central unit; receiving, during and / or after establishing the second connection, cell information from the integrated access and backhaul node, the cell information indicating at least one of one or more neighboring cells and serving cells for the integrated access and backhaul node; as well as A third connection is established between the central unit and one or more base stations serving the serving cell and the at least one of the one or more neighboring cells.

40. A computer program product embodied in at least one computer-readable medium and comprising instructions that, when executed by at least one processor of an integrated access and backhaul node, cause the integrated access and backhaul node to at least: establishing a first connection between a mobile terminating component in the integrated access and backhaul node and a cell served by a serving node; establishing a second connection between a distributed unit in the integrated access and backhaul node and a central unit for controlling the integrated access and backhaul node; as well as Cell information is transmitted from the integrated access and backhaul node to the serving node, the cell information indicating cells served by the distributed unit in the integrated access and backhaul node.

41. A computer program product embodied in at least one computer readable medium and comprising instructions which, when executed by at least one processor of a radio access network node, cause the radio access network node to at least: receiving cell information from an integrated access and backhaul node, the cell information indicating cells served by a distributed unit in the integrated access and backhaul node; and Based on the received cell information, a third connection is established between the radio access network node and a central unit for controlling the integrated access and backhaul node, the central unit having a second connection with the distributed unit in the integrated access and backhaul node.

42. A computer program product embodied in at least one computer readable medium and comprising instructions which, when executed by at least one processor of a central unit, cause the central unit to at least: establishing a third connection between the central unit and a radio access network node; receiving, during and / or after establishing the third connection between the central unit and the radio access network node, neighboring cell information from the radio access network node, the neighboring cell information indicating one or more neighboring cells for an integrated access and backhaul node under control of the central unit; and A third connection is established between the central unit and one or more neighboring base stations, the one or more neighboring base stations supporting the one or more neighboring cells indicated in the neighboring cell information.

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