Method and apparatus for IAB node transition

Abstract

[0003] According to some embodiments of the present disclosure, a base station (BS) may determine whether there is an Internet Protocol (IP) connection between a second BS and a third BS, where one of the first BS and the second BS has a Radio Resource Control (RRC) connection to a Mobile Termination (MT) of a wireless network node and the other of the first BS and the second BS has an F1 connection to a Distributed Unit (DU) of the wireless network node, and, based on the determination, initiate a migration of the MT of the wireless network node to the third BS or a migration of the DU of the wireless network node to the third BS.

Description

[Technical Field]

[0001] FIELD Embodiments of the present disclosure relate generally to communications technologies, and more particularly to integrated access and backhaul (IAB) node migration. [Background technology]

[0002] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasting, and so on. Wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of wireless communication systems may include fourth-generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth-generation (5G) systems, sometimes referred to as New Radio (NR) systems.

[0003] To expand the coverage and availability of wireless communication systems (e.g., 5G systems), the Third Generation Partnership Project (3GPP®) envisions an integrated access and backhaul (IAB) architecture to support multi-hop relays. In an IAB network, an IAB node may hop through one or more IAB nodes before reaching a base station (also called an “IAB donor” or “donor node”). A single hop may be considered a special instance of multiple hops. Multi-hop backhauling is beneficial because it provides a relatively large coverage extension compared to single-hop backhauling. In relatively high-frequency wireless communication systems (e.g., radio signals transmitted in frequency bands above 6 GHz), relatively narrow or small signal coverage can benefit from multi-hop backhauling techniques. Summary of the Invention [Problem to be solved by the invention]

[0004] The industry wants technology to facilitate communication across the IAB network. [Means for solving the problem]

[0005] Some embodiments of the present disclosure provide a first base station (BS). The first BS may include a transceiver and a processor coupled to the transceiver. The processor may be configured to: determine whether there is an Internet Protocol (IP) connection between a second BS and a third BS, where one of the first BS and the second BS has a Radio Resource Control (RRC) connection to a Mobile Termination (MT) of a wireless network node and the other of the first BS and the second BS has an F1 connection to a Distributed Unit (DU) of the wireless network node; and, based on the determination, initiate a transition of the MT of the wireless network node to the third BS or a transition of the DU of the wireless network node to the third BS.

[0006] Some embodiments of the present disclosure provide a second BS. The second BS may include a processor and a transceiver coupled to the processor. The transceiver may be configured to receive, from a first BS, second information regarding IP connectivity to the first BS or an inquiry about the IP connectivity of the second BS, where one of the first BS and the second BS has an RRC connection to a wireless network node MT and the other of the first BS and the second BS has an FI connection to a wireless network node DU, and to transmit, to the first BS, the first information regarding IP connectivity to the second BS.

[0007] In some embodiments of the present disclosure, the first information includes a first list of BSs, each BS in the first list of BSs having IP connectivity to a second BS. In some embodiments of the present disclosure, the second information includes a second list of BSs, each BS in the second list of BSs having IP connectivity to the first BS.

[0008] Some embodiments of the present disclosure provide a third BS. The third BS may include a processor and a transceiver coupled to the processor. The transceiver may be configured to receive an inquiry from a first BS regarding whether there is IP connectivity between the third BS and a second BS, where one of the first BS and the second BS has an RRC connection to a wireless network node MT and the other of the first BS and the second BS has an FI connection to a wireless network node DU, and to send a response to the inquiry to the first BS.

[0009] In some embodiments of the present disclosure, in response to the response indicating that there is IP connectivity between the third BS and the second BS, the transceiver is further configured to receive a request from one of the first BS and the second BS to transition an MT of the wireless network node to the third BS, or receive a request from the other of the first BS and the second BS or the wireless network node to transition a DU of the wireless network node to the third BS.

[0010] Some embodiments of the present disclosure provide a first BS. The first BS may include a processor and a transceiver coupled to the processor. The transceiver may be configured to: transmit a request to the third BS to transition one of a MT and a DU of a wireless network node to a third BS, where the first BS connects to one of the MT and the DU of the wireless network node, and the request includes information associated with a second BS connecting to the other of the MT and the DU of the wireless network node; and receive a response to the request from the third BS.

[0011] In some embodiments of the present disclosure, the response indicates that the transition was rejected due to a lack of IP connectivity between the second BS and the third BS.

[0012] In some embodiments of the present disclosure, the information associated with the second BS includes an identifier of the second BS.

[0013] Some embodiments of the present disclosure provide a wireless network node that may include a processor and a transceiver coupled to the processor. The transceiver may be configured to: send a request to a third BS to trigger a transition of a DU of the wireless network node from a first BS to a third BS, where a MT of the wireless network node has an RRC connection to a second BS; and receive a response in response to the request.

[0014] Some embodiments of the present disclosure provide a method implemented by a first BS, which may include determining whether there is IP connectivity between a second BS and a third BS, where one of the first BS and the second BS has an RRC connection to a MT of the wireless network node and the other of the first BS and the second BS has an F1 connection to a DU of the wireless network node, and initiating a transition of the MT of the wireless network node to the third BS or a transition of the DU of the wireless network node to the third BS based on the determination.

[0015] Some embodiments of the present disclosure provide a method implemented by a second BS, which may include receiving, from a first BS, second information regarding IP connectivity to the first BS or an inquiry about the IP connectivity of the second BS, where one of the first BS and the second BS has an RRC connection to a wireless network node MT and the other of the first BS and the second BS has an FI connection to a wireless network node DU, and transmitting, to the first BS, the first information regarding IP connectivity to the second BS.

[0016] Some embodiments of the present disclosure provide a method implemented by a third BS, which may include receiving an inquiry from a first BS about whether there is IP connectivity between the third BS and a second BS, where one of the first BS and the second BS has an RRC connection to a wireless network node MT and the other of the first BS and the second BS has an FI connection to a wireless network node DU, and sending a response to the inquiry to the first BS.

[0017] Some embodiments of the present disclosure provide a method implemented by a first BS, which may include transmitting a request to a third BS to transition one of a MT and a DU of a wireless network node to a third BS, where the first BS connects to one of the MT and the DU of the wireless network node, and the request includes information associated with a second BS connecting to the other of the MT and the DU of the wireless network node, and receiving a response to the request from the third BS.

[0018] Some embodiments of the present disclosure provide a method implemented by a wireless network node, which may include sending a request to a third BS to trigger a transition of a DU of the wireless network node from a first BS to the third BS, where an MT of the wireless network node has an RRC connection to a second BS, and receiving a response in response to the request.

[0019] Some embodiments of the present disclosure provide an apparatus. According to some embodiments of the present disclosure, the apparatus may include at least one non-transitory computer-readable medium storing computer-executable instructions, at least one receiving circuit, at least one transmitting circuit, and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuit, and the at least one transmitting circuit, wherein the at least one non-transitory computer-readable medium and the computer-executable instructions, using the at least one processor, may be configured to cause the apparatus to perform a method according to some embodiments of the present disclosure.

[0020] Embodiments of the present disclosure provide technical solutions to facilitate and improve the implementation of various communication technologies, such as 5G NR.

[0021] To explain the manner in which the advantages and features of the present disclosure can be obtained, the disclosure will be described by reference to specific embodiments thereof that are illustrated in the accompanying drawings. These drawings illustrate only exemplary embodiments of the disclosure and therefore should not be considered limiting of its scope. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of a wireless communication system according to some embodiments of the present disclosure. [Figure 2] FIG. 2 is an example block diagram of a protocol stack for an IAB network, according to some embodiments of the present disclosure. [Figure 3] FIG. 2 is an example block diagram of a protocol stack for an IAB network, according to some embodiments of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of an IAB node transition according to some embodiments of the present disclosure. [Figure 5] FIG. 1 is a schematic diagram of an IAB node transition according to some embodiments of the present disclosure. [Figure 6]1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 7] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 8] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 9] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 10] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 11] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 12] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 13] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 14] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 15] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 16] 1 is a flowchart of an example procedure for wireless communication, according to some embodiments of the present disclosure. [Figure 17] FIG. 1 is a block diagram of an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0023] The detailed description of the accompanying drawings is intended as an illustration of preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure may be practiced. It is to be understood that the same or equivalent function may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present disclosure.

[0024] Reference will now be made in detail to several embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. For ease of understanding, the embodiments are provided under specific network architectures and new service scenarios, such as Third Generation Partnership Project (3GPP) 5G (NR), 3GPP Long Term Evolution (LTE) Release 8, etc. With the development of network architectures and new service scenarios, it is contemplated that all embodiments in the present disclosure are also applicable to similar technical challenges, and further, the terms listed in the present disclosure may change, which should not affect the principles of the present disclosure.

[0025] Compared with 4G communication systems, 5G communication systems impose stricter requirements on various network performance indicators, such as a 1000-fold increase in capacity, wider coverage requirements, ultra-high reliability, and ultra-low latency. Given the abundant frequency resources of high-frequency carriers, the use of high-frequency small-scale station deployments is becoming increasingly common in hotspot areas to meet the ultra-high capacity needs of 5G. However, high-frequency carriers have poor propagation characteristics, severe attenuation due to obstacles, and limited coverage. Therefore, dense deployment of small-scale stations is required. In addition, deploying optical fiber can be difficult and expensive for these small-scale stations. Therefore, an economical and convenient backhaul method is needed. Integrated access and backhaul (IAB) technology, in which both access links and backhaul links can use wireless transmission solutions to avoid fiber deployment, offers an idea for solving the above challenges.

[0026] In an IAB network, a wireless network node, such as a relay node (RN) or IAB node or wireless backhaul node / device, can provide wireless access service for a UE. For example, a UE can connect to an IAB donor relayed by one or more IAB nodes. The IAB donor may also be referred to as a donor node or donor base station (e.g., DgNB, Donor gNodeB). In addition, a wireless link between an IAB donor and an IAB node or a wireless link between different IAB nodes may be referred to as a "backhaul link." Wireless network nodes in an IAB network may be stationary or mobile. Embodiments of the present disclosure may be applied to wireless network nodes regardless of whether the wireless network node is stationary or mobile.

[0027] An IAB node may include an IAB mobile terminal (MT) portion and an IAB distribution unit (DU) portion. When an IAB node connects to its parent node (which may be another IAB node or an IAB donor), the IAB node may be considered in the role of a UE, i.e., an MT. When an IAB node provides services to its child node (which may be another IAB node or a UE), the IAB node may be considered in the role of a network device, i.e., a DU.

[0028] An IAB donor may be an access network element with complete base station functionality, or an access network element with a separate centralized unit (CU) and distributed unit (DU). The IAB donor may be connected to a core network (e.g., connected to a 5G core (5GC) network) and provide wireless backhaul functionality for IAB nodes. The CU of the IAB donor may be referred to as an "IAB donor CU" (or directly as a "CU"), and the DU of the IAB donor may be referred to as an "IAB donor DU." The IAB donor CU may be divided into a control plane (CP) and a user plane (UP). For example, a CU may include one CU-CP and one or more CU-UPs.

[0029] Considering the limited coverage of high frequency bands and to guarantee the coverage performance of the network, multi-hop networking can be adopted in the IAB network. Taking into account the requirements of service transmission reliability, IAB nodes can support dual connectivity (DC) or multi-connectivity to improve transmission reliability and deal with abnormal situations that may occur on the backhaul (BH) link, such as radio link failure (RLF) or jamming, load fluctuation, etc.

[0030] If an IAB network supports multi-hop and dual connectivity networking, there may be multiple transmission paths between a UE and an IAB donor. A transmission path may include multiple nodes, such as a UE, one or more IAB nodes, and an IAB donor (if the IAB donor is in the form of separate CU and DU, the IAB donor may also include an IAB donor DU and an IAB donor CU). Each IAB node may treat a neighboring node that provides backhaul services for the IAB node as a parent node (or parent IAB node), and each IAB node may be considered a child node (or child IAB node) of its parent node.

[0031] FIG. 1 illustrates a schematic diagram of a wireless communication system 100 in accordance with some embodiments of the present disclosure.

[0032] 1, wireless communications system 100 may include several base stations (e.g., IAB donor 110A and IAB donor 110B), several IAB nodes (e.g., IAB node 120A, IAB node 120B, and IAB node 120C), and several UEs (e.g., UE 130A and UE 130B). Although a particular number of UEs, IAB nodes, and IAB donors are illustrated in FIG. 1, it is contemplated that any number of UEs, IAB nodes, and IAB donors may be included in wireless communications system 100.

[0033] Each of IAB donor 110A, IAB donor 110B, IAB node 120A, IAB node 120B, and IAB node 120C may be directly connected to one or more IAB nodes according to some other embodiments of the present disclosure. Each of IAB donor 110A, IAB donor 110B, IAB node 120A, IAB node 120B, and IAB node 120C may be directly connected to one or more UEs according to some other embodiments of the present disclosure.

[0034] The UEs 130A and 130B may be any type of device configured to operate and / or communicate in a wireless environment. For example, the UEs 130A and 130B may include computing devices such as desktop computers, laptop computers, personal digital assistants (PDAs), tablet computers, smart televisions (e.g., televisions connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), in-vehicle computers, network devices (e.g., routers, switches, and modems). According to some embodiments of the present disclosure, the UEs 130A and 130B may include portable wireless communication devices, smartphones, cellular telephones, flip phones, devices with subscriber identity modules, personal computers, selective call receivers, or any other devices capable of transmitting and receiving communication signals over a wireless network. In some embodiments of the present disclosure, the UEs 130A and 130B may include wearable devices such as smart watches, fitness bands, optical head-mounted displays, Internet of Things (IoT) devices, etc. Additionally, UE 130A and UE 130B may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, wireless terminals, fixed terminals, subscriber stations, user terminals, or devices, or may be described using other terms used in the art.

[0035] The IAB donors 110A and 110B may be in communication with a core network (not shown in FIG. 1). The core network (CN) may include multiple core network components, such as a mobility management entity (MME) (not shown in FIG. 1) or an access and mobility management function (AMF) (not shown in FIG. 1). The CN may act as a gateway for UEs to access the public switched telephone network (PSTN) and / or other networks (not shown in FIG. 1).

[0036] The wireless communication system 100 may be compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, the wireless communication system 100 may be compatible with a wireless communication network, a cellular telephone network, a time division multiple access (TDMA)-based network, a code division multiple access (CDMA)-based network, an orthogonal frequency division multiple access (OFDMA)-based network, an LTE network, a 3GPP-based network, a 3GPP 5G network, a satellite communication network, a high altitude platform network, and / or other communication networks.

[0037] In some embodiments of the present disclosure, the wireless communication system 100 is compatible with the 3GPP protocol 5G NR. For example, the IAB donors 110A and 110B may transmit data using an orthogonal frequency division multiplexing (OFDM) modulation scheme on the DL. The UEs 130A and 130B may transmit data using a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) or cyclic prefix OFDM (CP-OFDM) scheme on the UL. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocol, such as WiMAX, among other protocols.

[0038] Those skilled in the art should understand that as technology develops and advances, the terms described in the present disclosure may change, but this should not affect or limit the principles and spirit of the present disclosure.

[0039] Referring to FIG. 1, IAB node 120A may be directly connected to IAB donors 110A and 110B, and IAB node 120B may be directly connected to IAB donor 110A. IAB donors 110A and 110B are parent nodes of IAB node 120A, and IAB donor 110A is the parent node of IAB node 120B. In other words, IAB nodes 120A and 120B are child IAB nodes of IAB donor 110A, and IAB node 120A is also a child IAB node of IAB donor 110B. IAB node 120C can reach IAB donor 110A by hopping through IAB node 120B. IAB node 120B is the parent IAB node of IAB node 120C. In other words, IAB node 120C is a child IAB node of IAB node 120B.

[0040] In some other embodiments of the present disclosure, an IAB node may be connected to IAB node 120C so that the IAB node can reach IAB donor 110A by hopping through IAB node 120C and IAB node 120B. This IAB node and IAB node 120C may be referred to as descendant IAB nodes of IAB node 120B.

[0041] UEs 130A and 130B may be connected to IAB nodes 120A and 120C, respectively. Accordingly, IAB nodes 120A and 120C may be referred to as access IAB nodes. Uplink (UL) packets (e.g., data or signaling) from UE 130A or UE 130B may be transmitted to an IAB donor (e.g., IAB donor 110A or 110B) via one or more IAB nodes and then transmitted by the IAB donor to a mobile gateway device (such as a user plane function (UPF) in 5GC). Downlink (DL) packets (e.g., data or signaling) may be transmitted from the IAB donor (e.g., IAB donor 110A or 110B) after being received by the gateway device and then transmitted to UE 130A or 130B through one or more IAB nodes.

[0042] 1, UE 130A may transmit UL data to or receive DL data from IAB donor 110A or 110B via IAB node 120A. UE 130B may transmit UL data to or receive DL data from IAB donor 110A via IAB node 120C and IAB node 120B.

[0043] In an IAB deployment such as wireless communication system 100, a wireless link between an IAB donor (e.g., IAB donor 110A or 110B in FIG. 1) and an IAB node or between two IAB nodes may be referred to as a backhaul link (BL). A wireless link between an IAB donor (e.g., IAB donor 110A or 110B in FIG. 1) and a UE or between an IAB node and a UE may be referred to as an access link (AL). For example, in FIG. 1, wireless links 140A to 140D are BLs, and wireless links 150A and 150B are ALs.

[0044] A backhaul adaptation protocol (BAP) layer, which is a protocol layer above the radio link control (RLC) layer, is introduced into the IAB system and can be used to realize packet routing, bearer mapping, and flow control on the wireless backhaul link.

[0045] An F1 interface may be established between an IAB node (e.g., a DU portion of the IAB node) and an IAB donor (e.g., an IAB donor CU). The F1 interface may support both user plane protocols (e.g., F1-U) and control plane protocols (e.g., F1-C). The user plane protocols of the F1 interface may include one or more of General Packet Radio Service (GPRS) Tunneling Protocol User Plane (GTP-U), User Datagram Protocol (UDP), Internet Protocol (IP), and other protocols. The control plane protocols of the F1 interface may include one or more of F1 Application Protocol (F1AP), Stream Control Transport Protocol (SCTP), IP, and other protocols.

[0046] Through the control plane of the F1 interface, the IAB node and the IAB donor can perform, for example, interface management, IAB-DU management, and UE context-related configuration. Through the user plane of the F1 interface, the IAB node and the IAB donor can perform, for example, user plane data transmission and downlink transmission status feedback functions.

[0047] Figure 2 shows an example block diagram of a user plane (UP) protocol stack 200 for an IAB network, in accordance with some embodiments of the present disclosure. Figure 3 shows an example block diagram of a control plane (CP) protocol stack 300 for an IAB network, in accordance with some embodiments of the present disclosure. In Figures 2 and 3, a UE may be connected to an IAB donor via IAB node 2 and IAB node 1. In some other embodiments of the present disclosure, a UE may be connected to an IAB donor via more or fewer IAB nodes.

[0048] 2, the UP protocol stack of the UE may include a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. The UP protocol stack of the DU of IAB node 2 may include a GTP-U layer, a UDP layer, an IP layer, an RLC layer, a MAC layer, and a PHY layer. The UP protocol stack of the MT of IAB node 2 or the DU or MT of IAB node 1 may include a BAP layer, an RLC layer, a MAC layer, and a PHY layer. The UP protocol stack of the DU of the IAB donor may include an IP layer, a BAP layer, an RLC layer, a MAC layer, and a PHY layer, with the PHY layer belonging to Layer 1 (L1) and the BAP layer, RLC layer, and MAC layer belonging to Layer 2 (L2). The protocol stack of IAB Donor CU-UP may include a GTP-U layer, a UDP layer, an IP layer, an SDAP layer, a PDCP layer, an L2 layer, and an L1 layer.

[0049] Referring to Figure 3, the CP protocol stack of the UE may include a radio resource control (RRC) layer, a PDCP layer, an RLC layer, a MAC layer, and a physical (PHY) layer. The CP protocol stack of the DU of IAB node 2 may include an F1AP layer, an SCTP layer, an IP layer, an RLC layer, a MAC layer, and a PHY layer. The CP protocol stack of the MT of IAB node 2 or the DU or MT of IAB node 1 may include a BAP layer, an RLC layer, a MAC layer, and a PHY layer. The CP protocol stack of the DU of the IAB donor may include an IP layer, a BAP layer, an RLC layer, a MAC layer, and a PHY layer, with the PHY layer belonging to L1 and the BAP layer, RLC layer, and MAC layer belonging to L2. The protocol stack of the CU-CP of the IAB donor may include an RRC layer, a PDCP layer, an F1AP layer, an SCTP layer, an IP layer, an L2 layer, and an L1 layer.

[0050] The protocol stacks shown in Figures 2 and 3 are for illustrative purposes only. For example, the sequence of some of the protocol layers in the protocol stacks of Figures 2 and 3 may be rearranged for illustrative purposes. For example, the SDAP and PDCP layers belong to L2, but these layers are shown above the GTP-U, UDP, and IP layers in the protocol stack of IAB Donor CU-UP in Figure 2.

[0051] Signals between each node in the IAB network may include, for example, the following, which may be applicable to the present disclosure: - IAB Donor CU and IAB Donor DU: F1AP message, - IAB donor CU and IAB node: F1AP messages between CU and IAB-DU or RRC messages between CU and IAB-MT; - IAB Donor CU and UE: RRC messages, - Access IAB nodes and UEs: L2 control PDUs, such as MAC Control Elements (CEs) or RLC control PDUs, and - An IAB node and another child or parent IAB node: L2 control PDUs such as MAC CE, RLC control PDUs, or BAP control PDUs.

[0052] As demand for improved cellular coverage and connectivity continues to grow, communications in outdoor and mobility scenarios may face additional challenges. In some embodiments of the present disclosure, a mobile wireless network node acting as a relay between a UE and a 3GPP communication network (e.g., 5G) may be employed to facilitate communications in such scenarios. The mobile wireless network node may, for example, provide an access link to the UE, wirelessly connected (e.g., using NR) to a core network through a BS (e.g., a donor Next Generation Radio Access Network (NG-RAN)). In some examples, such a mobile wireless network node may also be referred to as a mobile base station relay or mobile relay. The above description of the wireless network node and IAB node may apply to the mobile base station relay. That is, the mobile base station relay may be a mobile IAB node.

[0053] In some examples, a mobile base station relay may be mounted on a vehicle. The mobile base station relay may serve UEs that are inside or outside the vehicle or that enter or leave the vehicle. In the context of this disclosure, inside or outside the mobile base station relay may mean inside or outside the vehicle or other device on which the mobile wireless network node is mounted.

[0054] In some examples, the radio links used between the mobile base station relay and the served UE and between the mobile base station relay and the BS may be Uu links (e.g., NR-Uu) different from the UE relay (e.g., providing indirect connectivity to remote UEs using a PC5-based link). In some examples, there may be at least one hop between the UE and the mobile base station relay. In some examples, there may be at least one hop between the mobile base station relay and the BS.

[0055] The adoption of such mobile wireless network nodes is advantageous in various aspects and can be applied to various scenarios. For example, in some outdoor environments, the availability of vehicles equipped with mobile base station relays following certain known / predictable itineraries (e.g., buses, trams, etc.) or located at convenient locations (e.g., outdoor stadiums, hotspot areas, or emergency sites) can significantly increase cellular coverage and capacity on an ad-hoc basis when or where needed. These relays may, for example, use 5G wireless backhaul toward the macro network, thus providing better coverage and connectivity to nearby UEs. Mobile relays are also well suited to improving connectivity for users or devices inside vehicles equipped with mobile relays in different environments, for example, for passengers in buses, cars / taxis, or trains, or for special / specialized personnel or equipment. Such mobile wireless network nodes may also be used to reach users or devices that would otherwise have no or very poor macro coverage, for example, in the case of first responders who have moved into indoor buildings / areas, using relays located nearby or in outdoor vehicles to obtain the necessary coverage and connectivity.

[0056] The technical benefits of using such mobile wireless network nodes further include, among other things, the ability to leverage better radio frequency, antenna, and power capabilities to obtain better macro coverage than nearby UEs. Additionally, besides the value to network operators and end users, valuable incentives may also be found for other parties, for example, vehicle manufacturers, and vehicle and fleet owners or providers, to install and operate relays in their vehicles.

[0057] Due to the mobility of wireless network nodes (eg, IAB nodes), the wireless network nodes may need to transition (or handover) from one IAB donor to another IAB donor.

[0058] In some embodiments, an MT of a wireless network node may transition from an initial (source) IAB donor to a new (target) IAB donor. For example, an MT of a wireless network node may transition to a different parent node under a different CU of the IAB donor. For example, referring back to FIG. 1 , an MT of IAB node 120C or IAB node 120B may transition from IAB donor 110A to IAB donor 110B. In this scenario, the DU of the wireless network node and the DU of the descendant node of the wireless network node may retain F1 connectivity with the source IAB donor (e.g., the CU of the source IAB donor). This transition may be referred to as an inter-donor partial transition. The wireless network node whose MT transitions to the target IAB donor (e.g., the CU of the target IAB donor) may be referred to as a boundary wireless network node. After the inter-donor partial transition, F1 traffic of the DU of the wireless network node and the DU of the descendant node of the wireless network node may be routed, for example, via the BAP layer of the IAB topology to which the MT of the wireless network node transitioned.

[0059] In some embodiments, a DU of a wireless network node may transition from an initial (source) IAB donor to a new (target) IAB donor. This transition may be referred to as an inter-donor IAB-DU transition. In some embodiments, to perform a handover of a UE served by a wireless network node (e.g., its DU), the wireless network node may simultaneously support two logical DUs (e.g., DU #1 and DU #2), each of which may have an F1AP association with the source IAB donor (e.g., a CU of the source IAB donor) and the target IAB donor (e.g., a CU of the target IAB donor). A UE connected to the wireless network node may be handed over from a cell of DU #1 (i.e., a source DU of the wireless network node) that has an F1AP association with the source CU (i.e., a CU of the source IAB donor) to a cell of DU #2 (i.e., a target DU of the wireless network node) that has an F1AP association with the target CU (i.e., a CU of the target IAB donor). After the DU transitions to the wireless network node, the F1 interface between DU #1 and the source IAB donor may be released.

[0060] In some embodiments of the present disclosure, the migration of a DU of a wireless network node may be performed independently from the migration of an MT of the wireless network node. For example, the DU and MT of the wireless network node may be migrated (or handed over) to different IAB donors (e.g., donor CUs).

[0061] For example, Figures 4 and 5 show schematic diagrams of IAB node transition according to some embodiments of the present disclosure. In the example of Figure 4, an MT of a wireless network node transitions from one BS to another BS, while a DU of the wireless network node connects to yet another BS (hereinafter, "Scenario 1"). In the example of Figure 5, a DU of a wireless network node transitions from one BS to another BS, while an MT of the wireless network node connects to yet another BS (hereinafter, "Scenario 2"). The details described in all of the above embodiments of the present disclosure are applicable to the embodiments shown in Figures 4 and 5.

[0062] Referring to FIG. 4, IAB donor 410A may include CU 475 and DU 465, IAB donor 410B may include CU 476 and DU 466, and IAB donor 410C may include CU 477 and DU 467. IAB node 420A may be directly connected to IAB donor 410A and may include MT 451 and DU 461. IAB node 420B may be directly connected to IAB donor 410B and may include MT 452 and DU 462. IAB node 420C may be directly connected to IAB donor 410C and may include MT 453 and DU 463. IAB node 420D may include MT 454 and DU 464, and UE 430 may be connected to IAB node 420D. IAB node 420D may be referred to as UE 430's access IAB node.

[0063] DU 464 of IAB node 420D may be anchored in IAB donor 410C (e.g., CU 477). MT 454 of IAB node 420D may be migrated (or handed over) from IAB donor 410A to IAB donor 410B. During the migration of MT 454, F1 transport between DU 464 and IAB donor 410C is switched from the topology of IAB donor 410A (e.g., as shown by signaling flow 440A) to the topology of IAB donor 410B (e.g., as shown by signaling flow 440B).

[0064] 5, IAB donor 510A may include CU 575 and DU 565, IAB donor 510B may include CU 576 and DU 566, and IAB donor 510C may include CU 577 and DU 567. IAB node 520A may be directly connected to IAB donor 510A and may include MT 551 and DU 561. IAB node 520B may be directly connected to IAB donor 510B and may include MT 552 and DU 562. IAB node 520C may be directly connected to IAB donor 510C and may include MT 553 and DU 563. IAB node 520D may include MT 554 and two DUs (DU 564a and DU 564b), and UE 530 may be connected to IAB node 520D. IAB node 520D may be referred to as UE 530's access IAB node.

[0065] The MT 554 of IAB node 520D may be anchored at IAB donor 510B (e.g., CU 576). The DU of IAB node 520D may be migrated from IAB donor 510A (i.e., source IAB donor) to IAB donor 510C (i.e., target IAB donor). Before DU migration, only DU 564a of IAB node 520D has an F1 connection to IAB donor 510A (e.g., shown by signaling flow 540A). During DU migration, IAB node 520D may have two DUs (e.g., DU 564a and DU 564b as shown in FIG. 5). DU 564a may have an F1 connection to IAB donor 510A, and DU 564b may have an F1 connection to IAB donor 510C (e.g., shown by signaling flow 540B). And after the DU transition, only DU 564b of IAB node 520D has an F1 connection to IAB donor 510C. Both F1 connections are transported over the topology of IAB donor 510B.

[0066] 4 and 5 are for illustrative purposes only. For example, in some other embodiments, the MT and DU of a wireless network node may be anchored at the same BS (e.g., IAB donor), and the MT or DU of a wireless network node may transition from a source BS to a target BS (e.g., IAB donor). For example, in some other embodiments, the wireless network node may hop through one or more wireless network nodes (e.g., IAB nodes) before reaching the source BS or target BS, or may be directly connected to the source BS or target BS.

[0067] Although the embodiments of the present disclosure are discussed based on some specific components (e.g., IAB donors or mobile IAB nodes) under a specific network architecture (e.g., IAB architecture), it should be noted that the embodiments of the present disclosure are also applicable to other similar network architectures and new service scenarios.

[0068] Several issues need to be resolved during wireless network node migration (eg, DU migration or MT migration).

[0069] For example, in both scenario 1 (e.g., as shown in FIG. 4) and scenario 2 (e.g., as shown in FIG. 5), the MT and DU of a wireless network node are terminated at different BSs after a transition. As a prerequisite for achieving this, the two BSs should have IP connectivity between them so that the MT and DU of the wireless network node can terminate at those BSs. Therefore, a problem that needs to be solved is whether such IP connectivity information should be obtained before a transition to ensure a successful transition. For example, referring to FIG. 4, whether IAB donor 410A should know whether there is IP connectivity between IAB donor 410B and IAB donor 410C before a transition of MT 454 of IAB node 420D. For example, referring to FIG. 5, whether IAB donor 510A should know whether there is IP connectivity between IAB donor 510B and IAB donor 510C before a transition of a DU of IAB node 520D. Furthermore, how to obtain such information needs to be solved.

[0070] For example, the MT and DU of a wireless network node may terminate at different BSs, and the F1-terminating BS to which the DU of the wireless network node connects may trigger a migration of the DU of the wireless network node. A problem that needs to be solved is how the F1-terminating BS can decide whether to implement a migration of the DU of the wireless network node to another BS. For example, referring to Figure 5, how should IAB donor 510A decide whether to trigger a migration of the DU of IAB node 520D?

[0071] For example, the MT and DU of a wireless network node may terminate at different BSs, and the transition of the DU of the wireless network node may not be triggered by the F1 terminating BS to which the DU of the wireless network node connects. The problem that needs to be solved is how the F1 terminating BS can be made aware of the completion of the DU transition and the target BS of the transition so that the F1 terminating BS can trigger a handover for the UE served by the wireless network node to the target BS. For example, referring to Figure 5, how can IAB donor 510A be aware of the completion of the transition of the DU of IAB node 520D and IAB donor 510C?

[0072]

[0013] The embodiments of the present disclosure provide a solution for improving the transition of wireless network nodes, which can solve at least the above problems. Further details regarding the embodiments of the present disclosure are described in the following text in combination with the accompanying drawings.

[0073] In some embodiments of the present disclosure, a DU of a network node may perform a transition from one BS (i.e., a source F1-terminated BS) to another BS (i.e., a target F1-terminated BS). An MT of the network node may connect to yet another BS (i.e., an RRC-terminated BS). As described above, during such a transition, the network node may have two logical DUs with respective F1 connections to the source F1-terminated BS and the target F1-terminated BS, and both F1 connections need to be transported through the topology of the RRC-terminated BS. However, an error case may occur when a DU transition is triggered by a source F1-terminated BS that does not know whether there is IP connectivity between the RRC-terminated BS and the target F1-terminated BS (or IP connectivity between a DU of the RRC-terminated BS and a CU of the target F1-terminated BS). To solve this problem, the source F1-terminated BS may query the RRC-terminated BS or the target F1-terminated BS before triggering a DU transition. In addition, the source F1-terminated BS may obtain information to assist the source F1-terminated BS in initiating the transition of a DU of the network node.

[0074] For example, FIG. 6 illustrates a flowchart of an example procedure 600 for wireless communication in accordance with some embodiments of the present disclosure.

[0075] The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 6. For example, BSs 610A-610C may function as IAB donors as described above and may include a CU and at least one DU. Network node 620 may function as an IAB node as described above and may include an MT and at least one DU (e.g., one DU before and after a DU transition or two DUs during a DU transition).

[0076] A network node 620 (e.g., a DU of the network node 620) may have an F1 connection with a BS 610A (e.g., a CU of the BS 610A). A network node 620 (e.g., an MT of the network node 620) may have an RRC connection with a BS 610B (e.g., a CU of the BS 610B). The BSs 610A and 610B may be referred to as the F1-terminating BS and the RRC-terminating BS, respectively.

[0077] In some embodiments, the DU of network node 620 may perform a transition from BS 610A (i.e., source F1-terminating BS) to a target BS (i.e., target F1-terminating BS such as BS 610C), while the MT of network node 620 retains its connection with BS 610B. For example, BS 610A, BS 610B, BS 610C, and network node 620 may function as IAB donor 510A, IAB donor 510B, IAB donor 510C, and IAB node 520D of FIG. 5.

[0078] In some embodiments, before initiating the migration of the DUs of network node 620 to BS 610C, BS 610A may determine whether there is IP connectivity between BS 610B and BS 610C. As described in more detail below, the determination may be based on a query initiated by BS 610A to BS 610B or BS 610C.

[0079] In some embodiments of the present disclosure, the BS 610A may need to be aware of the location of the MTs in the network node 620 to assist the BS 610A in determining whether to transition the DUs in the network node 620. For example, to assist the BS 610A in initiating a transition of the DUs in the network node 620, the network node 620 may transmit location information of the MTs in the network node 620 to the BS 610A in operation 611a. The information may be transmitted via an F1 interface between the DUs in the network node 620 and the BS 610A. In some embodiments, in addition to or instead of operation 611a, the BS 610B (i.e., the RRC terminating BS) may transmit location information of the MTs in the network node 620 to the BS 610A in operation 611b. The information may be transmitted via an Xn interface between the BS 610A and the BS 610B.

[0080] In some embodiments of the present disclosure, in operation 613a, BS610A may send to BS610B an inquiry about IP connectivity of BS610B (e.g., an inquiry about whether there is IP connectivity between BS610B and BS610C). In some embodiments of the present disclosure, in addition to or instead of operation 613a, BS610A may send to BS610C an inquiry about IP connectivity of BS610C (e.g., an inquiry about whether there is IP connectivity between BS610B and BS610C) in operation 613b. The inquiry may be sent over the Xn interface between BS610A and BS610B or between BS610A and BS610C.

[0081] If operation 613a is performed, BS 610B may send a response to the query to BS 610A in operation 615a. If operation 613b is performed, BS 610C may send a response to the query to BS 610A in operation 615b. BS 610A may then determine, based on the response, whether to trigger a migration of a DU of network node 620 from BS 610A to BS 610C. For example, if the response indicates that there is IP connectivity between BS 610B and BS 610C (i.e., positive feedback), BS 610A may initiate a migration of a DU of network node 620 to BS 610C. Otherwise, if the response indicates that there is no IP connectivity between BS 610B and BS 610C (i.e., negative feedback), BS 610A may not initiate a migration of a DU of network node 620 to BS 610C.

[0082] In some embodiments, BS 610A may send a transition command to network node 620 to initiate transition of the DUs of network node 620 to BS 610C (not shown in FIG. 6). Network node 620 may have two logical DUs (shown as DU #A1 and DU #A2), where DU #A1 has an F1 connection to BS 610A and DU #A2 may set up an F1 connection to BS 610C via a BH link under BS 610B. After DU #A2's cell is activated, all UEs connected to DU #A1 may perform handover from DU #A1's cell to DU #A2's cell.

[0083] In some other embodiments, BS 610A may send a transition command (eg, a DU or F1 transition request) to BS 610C to initiate the transition of the DU of network node 620 to BS 610C.

[0084] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 600 may be changed and that some of the operations in the exemplary procedure 600 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0085] In some embodiments of the present disclosure, a MT of a network node may perform a transition from one BS (i.e., a source RRC terminating BS) to another BS (i.e., a target RRC terminating BS). A DU of the network node may connect to yet another BS (i.e., an F1 terminating BS). As described above, during such a transition, the F1 transport between the DU of the network node and the F1 terminating BS is switched from the topology of the source RRC terminating BS to the topology of the target RRC terminating BS. However, an error case may arise when the MT transition is triggered by a source RRC terminating BS that does not know whether there is IP connectivity between the target RRC terminating BS and the F1 terminating BS (or IP connectivity between the DU of the target RRC terminating BS and the CU of the F1 terminating BS). To solve this problem, the source RRC terminating BS may query the target RRC terminating BS or the F1 terminating BS for IP connectivity before triggering the MT transition.

[0086] For example, FIG. 7 illustrates a flowchart of an example procedure 700 for wireless communication, in accordance with some embodiments of the present disclosure.

[0087] The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 7. For example, BSs 710A-710C may function as IAB donors as described above and may include a CU and at least one DU. Network node 720 may function as an IAB node as described above and may include an MT and at least one DU (e.g., one DU before and after a DU transition or two DUs during a DU transition).

[0088] A network node 720 (e.g., a DU of the network node 720) may have an F1 connection with a BS 710C (e.g., a CU of the BS 710C). A network node 720 (e.g., an MT of the network node 720) may have an RRC connection with a BS 710A (e.g., a CU of the BS 710A). The BSs 710C and 710A may be referred to as the F1-terminating BS and the RRC-terminating BS, respectively.

[0089] In some embodiments, the MT of network node 720 may perform a transition from BS 710A (i.e., source RRC terminating BS) to a target BS (i.e., target RRC terminating BS such as BS 710B), while the DU of network node 720 retains its connection with BS 710C. For example, BS 710A, BS 710B, BS 710C, and network node 720 may function as IAB donor 410A, IAB donor 410B, IAB donor 410C, and IAB node 420D of FIG. 4.

[0090] In some embodiments, BS710A may trigger a transition of the MT at network node 720 (e.g., to BS710B) based on measurement reports from the MT at network node 720. Before initiating a transition of the MT at network node 720 to BS710B, BS710A may determine whether there is IP connectivity between BS710B and BS710C. As described in more detail below, the determination may be based on a query initiated by BS710A to BS710B or BS710C.

[0091] In some embodiments of the present disclosure, in operation 713a, BS710A may send to BS710B an inquiry about IP connectivity of BS710B (e.g., an inquiry about whether there is IP connectivity between BS710B and BS710C). In some embodiments of the present disclosure, in addition to or instead of operation 713a, BS710A may send to BS710C an inquiry about IP connectivity of BS710C (e.g., an inquiry about whether there is IP connectivity between BS710B and BS710C) in operation 713b. The inquiry may be sent over the Xn interface between BS710A and BS710B or between BS710A and BS710C.

[0092] If operation 713a is performed, BS710B may send a response to the query to BS710A in operation 715a. If operation 713b is performed, BS710C may send a response to the query to BS710A in operation 715b. BS710A may then determine, based on the response, whether to trigger a transition of the MT of network node 720 from BS710A to BS710B. For example, if the response indicates that there is IP connectivity between BS710B and BS710C (i.e., positive feedback), BS710A may initiate a transition of the MT of network node 720 to BS710B. Otherwise, if the response indicates that there is no IP connectivity between BS710B and BS710C (i.e., negative feedback), BS710A may not initiate a transition of the MT of network node 720 to BS710B.

[0093] In some embodiments, BS710A may send a transition command (e.g., a handover command) to BS710B to initiate a transition of the MT of network node 720 to BS710B (not shown in FIG. 7). The MT of network node 720 may perform a transition (or handover) from BS710A to BS710B as a UE. The F1 transport between the DU of network node 720 and BS710C is switched from the topology of BS710A to the topology of BS710B.

[0094] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 700 may be changed and some of the operations in the exemplary procedure 700 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0095] In some embodiments of the present disclosure, a procedure between two BSs is introduced to exchange IP connectivity information between the two BSs. For example, the F1-terminated BS and the RRC-terminated BS of a network node may exchange such information over the Xn interface between them. Such a procedure may be triggered by either the F1-terminated BS or the RRC-terminated BS. The F1-terminated BS or the RRC-terminated BS may use the exchanged information to decide whether to initiate or implement a DU transition or MT transition of the network node to a different BS.

[0096] 8A and 8B show flowcharts of example procedures 800A and 800B for wireless communication according to some embodiments of the present disclosure. The example procedures 800A and 800B may be used to exchange IP connectivity information of two BSs.

[0097] The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figures 8A and 8B. For example, BSs 810A and 810B may function as IAB donors as described above and may include a CU and at least one DU.

[0098] In some embodiments of the present disclosure, BSs 810A and 810B may be F1-terminated BSs and RRC-terminated BSs of a network node (not shown in FIG. 8). That is, a network node (e.g., a DU of a network node) may have an F1 connection with BS 810A (e.g., a CU of BS 810A), and a network node (e.g., an MT of a network node) may have an RRC connection with BS 810B (e.g., a CU of BS 810B).

[0099] 8A , BS810A may transmit information (denoted as information #A1) regarding IP connectivity to BS810A to BS810B in operation 811. In some embodiments, information #A1 may include a list of BSs, each BS in the list having IP connectivity to BS810A. In response to receiving information #A1, BS810B may transmit information (denoted as information #A2) regarding IP connectivity to BS810B to BS810A in operation 813. In some embodiments, information #A2 may include a list of BSs, each BS in the list having IP connectivity to BS810B.

[0100] 8B, BS810B may transmit information (denoted as information #B1) regarding IP connectivity to BS810B to BS810A in operation 821. In some embodiments, information #B1 may include a list of BSs, each BS in the list having IP connectivity to BS810B. In response to receiving information #B1, BS810A may transmit information (denoted as information #B2) regarding IP connectivity to BS810A to BS810B in operation 823. In some embodiments, information #B2 may include a list of BSs, each BS in the list having IP connectivity to BS810A.

[0101] In some embodiments of the present disclosure, BS810A can use IP connectivity information to BS810B (e.g., information #A2 or information #B1) to determine whether to initiate a DU migration of the network node to a BS (denoted as BS #C1) that is different from both BS810A and BS810B. For example, BS810A can determine whether there is IP connectivity between BS810B and BS #C1 based on the IP connectivity information to BS810B, and can initiate a DU migration of the wireless network node to BS #C1 if it is determined that BS810B and BS #C1 have IP connectivity.

[0102] In some embodiments of the present disclosure, BS810B can use IP connectivity information to BS810A (e.g., information #A1 or information #B2) to determine whether to initiate MT migration of the network node to a BS (denoted as BS #C2) different from both BS810A and BS810B. For example, BS810B can determine whether there is IP connectivity between BS810B and BS #C2 based on the IP connectivity information to BS810A, and can initiate MT migration of the wireless network node to BS #C2 if it is determined that BS810B and BS #C2 have IP connectivity.

[0103] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedures 800A and 800B may be changed and some of the operations in the exemplary procedures 800A and 800B may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0104] As indicated above, the IP connectivity information may be obtained before the MT or DU transition of the network node is performed. For example, the MT or DU transition of the network node is performed only when the source RRC terminating BS or source F1 terminating BS obtains information that the target RRC terminating BS or target F1 terminating BS has IP connectivity to the F1 terminating BS or RRC terminating BS. However, in some other embodiments of the present disclosure, such information may not necessarily be obtained before the MT or DU transition of the network node.

[0105] For example, FIG. 9 illustrates a flowchart of an example procedure 900 for wireless communication, in accordance with some embodiments of the present disclosure.

[0106] The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 9. For example, BSs 910A and 910B may function as IAB donors as described above and may include a CU and at least one DU.

[0107] In some embodiments of the present disclosure, BS910A may be an RRC terminating BS of a network node (not shown in FIG. 9). That is, a network node (e.g., an MT of the network node) may have an RRC connection with BS910A (e.g., a CU of BS910A). A network node (e.g., a DU of the network node) may have an F1 connection with another BS (not shown in FIG. 9, denoted as BS #C3 for clarity).

[0108] 9, in operation 911, BS910A (i.e., source RRC terminating BS) may send a handover request to BS910B (i.e., target RRC terminating BS) to handover the network node's MT to BS910B. For example, BS910A and BS910B may function as IAB donor 410A and IAB donor 410B in FIG. 4. In some embodiments, the handover request may include information associated with BS #C3, which has an F1 connection to the network node. For example, the information may indicate an identifier of BS #C3.

[0109] In some embodiments of the present disclosure, if BS910B has IP connectivity to BS #C3, BS910B may accept the handover in operation 913 and may send a response to the handover request (e.g., positive feedback such as a handover request confirmation message) to BS910A in operation 915.

[0110] In some embodiments of the present disclosure, if BS910B does not have IP connectivity to BS #C3, BS910B may reject the handover in operation 913 and may send a response to the handover request (e.g., negative feedback such as a handover preparation failed message) to BS910A in operation 915. In some embodiments, the response may indicate that the handover (or transition) was rejected due to lack of IP connectivity between BS #C3 and BS910B. For example, the handover preparation failed message may include a cause value of lack of IP connectivity.

[0111] In some embodiments of the present disclosure, BS910A may be an F1 terminating BS of a network node (not shown in FIG. 9). That is, a network node (e.g., a DU of the network node) may have an F1 connection with BS910A (e.g., a CU of BS910A). A network node (e.g., an MT of the network node) may have an RRC connection with another BS (not shown in FIG. 9, denoted as BS #C4 for clarity).

[0112] 9, BS910A (i.e., source F1-terminating BS) may transmit a request (e.g., a DU or F1 transition request) to BS910B (i.e., target F1-terminating BS) in operation 911 to transition a DU of the network node to BS910B. For example, BS910A and BS910B may function as IAB donors 510A and 510C of FIG. 5. In some embodiments, the request may include information associated with BS #C4, which has an RRC connection to the network node. For example, the information may indicate an identifier of BS #C4.

[0113] In some embodiments of the present disclosure, if BS910B has IP connectivity to BS #C4, BS910B may accept the request in operation 913 and may send a response to the request (e.g., positive feedback) to BS910A in operation 915.

[0114] In some embodiments of the present disclosure, if BS910B does not have IP connectivity to BS #C4, BS910B may reject the request in operation 913 and may send a response to the request (e.g., negative feedback) to BS910A in operation 915. In some embodiments, the response may indicate that the transition was rejected due to lack of IP connectivity between BS #C4 and BS910B. For example, the response message may indicate a cause value of lack of IP connectivity.

[0115] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 900 may be changed and that some of the operations in the exemplary procedure 900 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0116] For example, FIG. 10 illustrates a flowchart of an example procedure 1000 for wireless communication in accordance with some embodiments of the present disclosure.

[0117] The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 10. For example, BSs 1010A and 1010B may function as IAB donors as described above and may include a CU and at least one DU. Network node 1020 may function as an IAB node as described above and may include an MT and at least one DU (e.g., one DU before and after a DU transition or two DUs during a DU transition).

[0118] The network node 1020 (e.g., a DU of the network node 1020) may have an F1 connection with the BS 1010A (e.g., a CU of the BS 1010A). The network node 1020 (e.g., an MT of the network node 1020) may have an RRC connection with the BS 1010B (e.g., a CU of the BS 1010B). The BSs 1010A and 1010B may be referred to as the F1-terminating BS and the RRC-terminating BS, respectively.

[0119] In some embodiments, the DU of network node 1020 may perform a transition from BS 1010A (i.e., the source F1-terminating BS) to the target BS (i.e., the target F1-terminating BS, not shown in FIG. 10 and shown as BS #C5 for clarity), while the MT of network node 1020 retains its connection with BS 1010B. For example, BS 1010A, BS 1010B, and network node 1020 may function as IAB donor 510A, IAB donor 510B, and IAB node 520D of FIG. 5.

[0120] In some embodiments, the migration of a DU of the network node 1020 may be triggered by an F1 terminating BS (e.g., BS 1010A) of the network node 1020. In some embodiments, the migration of a DU of the network node 1020 may not be triggered by an F1 terminating BS (e.g., BS 1010A) of the network node 1020. For example, the migration may be triggered by the network node 1020 itself or by an operations, administration, and maintenance (OAM) entity.

[0121] For example, in some embodiments, BS 1010A may trigger a DU migration and send a migration command to network node 1020 to migrate that DU from BS 1010A to BS #C5. In some embodiments, to assist BS 1010A in determining whether to migrate a DU in network node 1020, BS 1010A may need to be aware of the location of an MT in network node 1020. For example, to assist BS 1010A in initiating a migration of a DU in network node 1020, BS 1010A may obtain location information of an MT in network node 1020 from network node 1020, BS 1010B, or both. For example, the location information may be obtained via an F1 interface between a DU in network node 1020 and BS 1010A. For example, the location information may be obtained via an Xn interface between BS 1010A and BS 1010B.

[0122] During migration of a DU of network node 1020, network node 1020 may have two logical DUs (shown as DU #B1 and DU #B2), where DU #B1 has an F1 connection to BS 1010A, and network node 1020 (e.g., DU #B2) may need to set up an F1 connection to BS #C5. In response to initiating or triggering a DU migration (e.g., receiving a migration command from BS 1010A or network node 1020 itself that triggers the DU migration), network node 1020 (e.g., DU #B2) may attempt to send an F1 setup request to BS #C5 (e.g., a CU of BS #C5). For example, DU #B2 may attempt to send an F1 setup request message to BS #C5 via BS 1010B. For example, in operation 1011, BS 1010B (e.g., a DU of BS 1010B) may receive an F1 setup request message from network node 1020.

[0123] In some embodiments, BS1010B (e.g., DU of BS1010B) cannot send an F1 setup request message to BS #C5 (e.g., CU of BS #C5) because there is no IP connectivity between BS1010B (e.g., DU of BS1010B) and BS #C5 (e.g., CU of BS #C5). In this case, the DU of BS1010B may notify the CU of BS1010B in operation 1013 with "Non-IP routable of UL packet for F1 setup request message" (which may be identified by source / target IP addresses).

[0124] Then, in operation 1015, BS 1010B (e.g., the CU of BS 1010B) may notify network node 1020 (e.g., the MT of network node 1020) of the failure to deliver the UL packet for the F1 setup request message to BS #C5 (which is identified by the target IP address). In some embodiments, the reason for the failure (i.e., no IP connectivity between BS #C5 and BS 1010B) may also be notified to network node 1020. For example, the message sent in operation 1015 may indicate a cause value of no IP connectivity.

[0125] If the DU transition is triggered by the network node 1020, the network node 1020 may, in response to receiving the information in operation 1015, cancel the DU transition to BS #C5 in operation 1017a.

[0126] If the DU transition is triggered by BS 1010A, the network node 1020 (e.g., DU #B1) may, in response to receiving the information in operation 1015, notify BS 1010A (e.g., CU of BS 1010A) about the failure of the F1 setup in operation 1017b. In some embodiments, the reason for the failure (i.e., no IP connectivity between BS #C5 and BS 1010B) may also be sent to BS 1010A. For example, the message sent in operation 1017b may indicate a cause value of no IP connectivity. Based on the information received in operation 1017b, BS 1010A may cancel the DU transition to BS #C5.

[0127] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1000 may be changed and that some of the operations in the exemplary procedure 1000 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0128] For example, FIG. 11 shows a flowchart of an example procedure 1100 for wireless communication, in accordance with some embodiments of the present disclosure.

[0129] The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 11. For example, BSs 1110A-1110C may function as IAB donors as described above and may include a CU and at least one DU. Network node 1120 may function as an IAB node as described above and may include an MT and at least one DU (e.g., one DU before and after DU transition or two DUs during DU transition).

[0130] The network node 1120 (e.g., a DU of the network node 1120) may have an F1 connection with the BS 1110A (e.g., a CU of the BS 1110A). The network node 1120 (e.g., an MT of the network node 1120) may have an RRC connection with the BS 1110B (e.g., a CU of the BS 1110B). The BSs 1110A and 1110B may be referred to as the F1-terminating BS and the RRC-terminating BS, respectively.

[0131] In some embodiments, the DU of network node 1120 may perform a transition from BS 1110A (i.e., source F1-terminating BS) to a target BS (i.e., target F1-terminating BS such as BS 1110C), while the MT of network node 1120 retains its connection with BS 1110B. For example, BS 1110A, BS 1110B, BS 1110C, and network node 1120 may function as IAB donor 510A, IAB donor 510B, IAB donor 510C, and IAB node 520D of FIG. 5.

[0132] In some embodiments, the transition of a DU of the network node 1120 may not be triggered by an F1 terminating BS (e.g., BS 1110A) of the network node 1120. For example, the transition may be triggered by the network node 1120 itself or by an OAM entity.

[0133] During migration of a DU of network node 1120, network node 1120 may have two logical DUs (shown as DU #C1 and DU #C2), where DU #C1 has an F1 connection to BS1110A, and network node 1120 (e.g., DU #C2) may need to set up an F1 connection to BS1110C. In response to the initiation or triggering of DU migration, network node 1120 (e.g., DU #C2) may attempt to send an F1 setup request to BS1110C (e.g., a CU of BS1110C). For example, DU #C2 may attempt to send an F1 setup request message to BS1110C via BS1110B. For example, in operation 1111, BS1110B (e.g., a DU of BS1110B) may receive an F1 setup request message from network node 1120.

[0134] In some embodiments, an F1 setup request in the context of this disclosure may also be referred to as a request for DU transition, a request to trigger DU transition, or other similar names.

[0135] In operation 1113, BS 1110B may send an F1 setup request message to BS 1110C, and network node 1120 (e.g., DU #C2) may set up an F1 connection to BS 1110C (e.g., a CU of BS 1110C) after receiving an F1 setup response message from BS 1110C. For example, network node 1120 may receive positive feedback in response to the F1 setup request (i.e., an F1 setup response message). After F1 setup, a cell on DU #C2 has been activated to serve the UE.

[0136] BS1110A needs to be notified of the F1 setup completion in order to transfer the UEs served by the cell of DU #C1 to the cell of DU #C2 (or in other words, transfer from BS1110A to BS1110C).

[0137] In some embodiments of the present disclosure, in operation 1115, network node 1120 may transmit a message to BS1110A indicating completion of F1 interface setup between network node 1120 and BS1110C (e.g., a CU of BS1110C) in response to receiving the response in operation 1113. For example, DU #C1 may notify the CU of BS1110A that DU #C2 has set up an F1 interface to BS1110C. In some embodiments, the message may include an identifier of BS1110C (e.g., an ID of a CU of BS1110C).

[0138] BS1110A may then trigger handover of UEs served by network node 1120 (e.g., DU #C1). For example, BS1110A may send at least one handover request to BS1110C (e.g., to the CU of BS1110C) based on the identifier of BS1110C. The handover request may be sent for each served UE or may be a group-based handover request for all served UEs.

[0139] In some other embodiments of the present disclosure, BS1110A (e.g., a CU of BS1110A) may receive an F1 interface setup complete indication from BS1110C (e.g., a CU of BS1110C). To accomplish this, network node 1120 may include (e.g., in operation 1111) an identifier of BS1110A (e.g., an ID of a CU of BS1110A) in an F1 setup request such that BS1110C (e.g., a CU of BS1110C) can send an F1 interface setup complete indication to BS1110A (e.g., a CU of BS1110A) (not shown in FIG. 11 ). The F1 interface setup complete indication may include information for identifying network node 1120 (e.g., a gNB-DU ID of network node 1120). In response to receiving the indication, BS1110A may trigger a handover of a UE served by network node 1120 (e.g., DU #C1) as described above. In these embodiments, operation 1115 may be omitted.

[0140] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1100 may be changed and that some of the operations in the exemplary procedure 1100 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0141] In some embodiments of the present disclosure, in response to a triggered transition of a DU of a network node (e.g., to a target F1-terminating BS, shown as BS #C6 for clarity), the network node may determine whether there is IP connectivity between the RRC-terminating BS of the network node (shown as BS #B6 for clarity) and BS #C6 before sending an F1 setup request. In these embodiments, the network node may terminate its F1 connection to BS #B6 or another BS. For example, the network node may send a query to BS #B6 regarding whether there is IP connectivity between BS #B6 and BS #C6. The transmission of the F1 setup request may be based on a response to the query from BS #B6. For example, if the response indicates no IP connectivity between BS #B6 and BS #C6 (e.g., negative feedback), the transition of the DU of the network node may be canceled. For example, if the response indicates there is IP connectivity between BS #B6 and BS #C6 (e.g., positive feedback), the network node may send an F1 setup request to BS #B6.

[0142] The above procedures used by a network node to obtain IP connectivity information may be applied to the above embodiments of the present disclosure. For example, in exemplary procedure 1000, network node 1020 may obtain such IP connectivity information before operation 1011. When negative feedback is obtained, operations 1011 to 1015 may be omitted. For example, in exemplary procedure 1100, network node 1120 may obtain such IP connectivity information before operation 1111. When positive feedback is obtained, network node 1120 may perform operation 1111.

[0143] It should be noted that the above procedure used by a network node to obtain IP connectivity information may not only be applicable to scenario 1 and scenario 2, but also to all cases when migration of a DU of a network node is triggered.

[0144] 12 shows a flowchart of an example procedure 1200 for wireless communication according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in FIG. 12. The example procedure 1200 may be performed by a BS (e.g., an IAB donor).

[0145] 12, in operation 1211, a BS (denoted as a first BS) may determine whether there is IP connectivity between another BS (denoted as a second BS) and yet another BS (denoted as a third BS), where one of the first BS and the second BS has an RRC connection to a wireless network node MT, and the other of the first BS and the second BS has an F1 connection to a wireless network node DU. In some examples, the wireless network node may be an IAB node. In some examples, the first BS, the second BS, and the third BS may be IAB donors.

[0146] In operation 1213, the first BS may initiate a transition of an MT of the wireless network node to the third BS or a transition of a DU of the wireless network node to the third BS based on the determination.

[0147] For example, a first BS may be the (source) RRC terminating BS for a wireless network node, a second BS may be the F1 terminating BS for the wireless network node, and the first BS may initiate a migration of an MT for the wireless network node to a third BS (i.e., target RRC terminating BS). For example, a second BS may be the RRC terminating BS for the wireless network node, but a first BS may be the (source) F1 terminating BS for the wireless network node, and the first BS may initiate a migration of a DU for the wireless network node to a third BS (i.e., target F1 terminating BS).

[0148] In some embodiments of the present disclosure, to determine whether there is IP connectivity between the second BS and the third BS, the first BS may initiate a query to the second BS, the third BS, or both, regarding whether there is IP connectivity between the second BS and the third BS, and may determine whether there is IP connectivity between the second BS and the third BS based on a response to the query from the second BS, the third BS, or both.

[0149] In some embodiments of the present disclosure, the first BS may receive location information of the MT of the wireless network node from the wireless network node or the second BS to assist the first BS in initiating a migration of the DU of the wireless network node.

[0150] In some embodiments of the present disclosure, a first BS may receive, from a second BS, first information regarding IP connectivity to the second BS, and a determination of whether there is IP connectivity between the second BS and a third BS is based on the first information.

[0151] In some embodiments of the present disclosure, the first BS may transmit to the second BS second information regarding IP connectivity to the first BS. In some examples, the second information is transmitted in response to receiving the first information. In some examples, the first information is received in response to transmitting the second information.

[0152] In some embodiments of the present disclosure, the first information includes a first list of BSs, each BS in the first list of BSs having IP connectivity to a second BS, and the second information includes a second list of BSs, each BS in the second list of BSs having IP connectivity to the first BS.

[0153] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1200 may be changed and that some of the operations in the exemplary procedure 1200 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0154] 13 shows a flowchart of an example procedure 1300 for wireless communication according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in FIG. 13. The example procedure 1300 may be performed by a BS (e.g., an IAB donor).

[0155] 13 , in operation 1311, a BS (denoted as a second BS) may receive, from another BS (denoted as a first BS), second information regarding IP connectivity to the first BS or an inquiry about the IP connectivity of the second BS, where one of the first BS and the second BS has an RRC connection to a wireless network node MT, and the other of the first BS and the second BS has an FI connection to a wireless network node DU. In some examples, the wireless network node may be an IAB node.

[0156] At operation 1313, the second BS may transmit to the first BS first information regarding IP connectivity to the second BS.

[0157] In some embodiments of the present disclosure, the first information is transmitted in response to a query, the query being about whether there is IP connectivity between the second BS and yet another BS (denoted as a third BS), and the first information indicating IP connectivity between the second BS and the third BS. In some examples, the first BS, the second BS, and the third BS may be IAB donors.

[0158] In some embodiments of the present disclosure, the second BS may transmit location information of the MT of the wireless network node to the first BS if the second BS has an RRC connection to the MT of the wireless network node.

[0159] In some embodiments of the present disclosure, the first information is transmitted in response to receiving the second information. In some embodiments of the present disclosure, the second information is received in response to transmitting the first information.

[0160] In some embodiments of the present disclosure, the first information includes a first list of BSs, each BS in the first list of BSs having IP connectivity to a second BS. In some embodiments of the present disclosure, the second information includes a second list of BSs, each BS in the second list of BSs having IP connectivity to the first BS.

[0161] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1300 may be changed and that some of the operations in the exemplary procedure 1300 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0162] 14 shows a flowchart of an example procedure 1400 for wireless communication according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in FIG. 14. The example procedure 1400 may be performed by a BS (e.g., an IAB donor).

[0163] 14, in operation 1411, a BS (denoted as a third BS) may receive an inquiry from another BS (denoted as a first BS) regarding whether there is IP connectivity between the third BS and yet another BS (denoted as a second BS), where one of the first BS and the second BS has an RRC connection to a wireless network node MT, and the other of the first BS and the second BS has an F1 connection to a wireless network node DU. In some examples, the wireless network node may be an IAB node. In some examples, the first BS, the second BS, and the third BS may be IAB donors.

[0164] At operation 1413, the third BS may send a response to the inquiry to the first BS.

[0165] In some embodiments of the present disclosure, in response to the response indicating that there is IP connectivity between the third BS and the second BS, the third BS may receive a request from one of the first BS and the second BS to migrate an MT of the wireless network node to the third BS, or may receive a request from the other of the first BS and the second BS or the wireless network node to migrate a DU of the wireless network node to the third BS.

[0166] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1400 may be changed and that some of the operations in the exemplary procedure 1400 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0167] Figure 15 shows a flowchart of an example procedure 1500 for wireless communication according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 15. The example procedure 1500 may be performed by a BS (e.g., an IAB donor).

[0168] 15, in operation 1511, one BS (denoted as a first BS) may send a request to another BS (denoted as a third BS) to transition one of the MT and DU of the wireless network node to a third BS, where the first BS connects to one of the MT and DU of the wireless network node, and the request includes information associated with yet another BS (denoted as a second BS) that connects to the other of the MT and DU of the wireless network node. In some examples, the wireless network node may be an IAB node. In some examples, the first BS, the second BS, and the third BS may be IAB donors.

[0169] At operation 1513, the first BS may receive a response to the request from the third BS.

[0170] In some embodiments of the present disclosure, the response indicates that the transition was rejected due to no IP connectivity between the second BS and the third BS. For example, the response may indicate a cause value of no IP connectivity.

[0171] In some embodiments of the present disclosure, the information associated with the second BS includes an identifier of the second BS. For example, the identifier may be an identifier of a CU of the second BS.

[0172] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1500 may be changed and that some of the operations in the exemplary procedure 1500 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0173] Figure 16 shows a flowchart of an example procedure 1600 for wireless communication according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiment shown in Figure 16. The example procedure 1600 may be performed by a network node (e.g., an IAB node).

[0174] Referring to FIG. 16, in operation 1611, the network node may send a request to a third BS to trigger a transition of a DU of the wireless network node from another BS (denoted as a first BS) to a BS (denoted as a third BS), and the MT of the wireless network node has an RRC connection to yet another BS (denoted as a second BS).

[0175] At operation 1613, the network node may receive a response in response to the request.

[0176] In some embodiments of the present disclosure, if the response confirms the request, the wireless network node may, in response to receiving the response, send to the first BS a message indicating completion of F1 interface setup between the wireless network node and the third BS. In some embodiments of the present disclosure, the message includes an identifier of the third BS.

[0177] In some embodiments of the present disclosure, the request includes an identifier of the first BS.

[0178] In some embodiments of the present disclosure, the wireless network node may send a query to the second BS as to whether there is IP connectivity between the second BS and a third BS, and sending the request is based on a response to the query from the second BS.

[0179] It will be appreciated by those skilled in the art that the sequence of operations in the exemplary procedure 1600 may be changed and that some of the operations in the exemplary procedure 1600 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0180] FIG. 17 illustrates a block diagram of an exemplary apparatus 1700 according to some embodiments of the present disclosure.

[0181] As shown in FIG. 17 , the apparatus 1700 may include at least one processor 1706 and at least one transceiver 1702 coupled to the processor 1706. The apparatus 1700 may be a network node (e.g., an IAB node), a BS (e.g., an IAB donor, an IAB donor CU, or an IAB donor DU), a DU of the BS, or a CU of the BS. If the apparatus 1700 is a BS, the apparatus 1700 may further include a CU and at least one DU coupled to the CU. The CU and DU may be co-located or separately located. The CU and DU may be coupled to the processor 1706. If the apparatus 1700 is a network node, the apparatus 1700 may further include a MT and a DU coupled to the MT. The MT and DU may be coupled to the processor 1706.

[0182] In this figure, elements such as at least one transceiver 1702 and processor 1706 are described in the singular, but the plural is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 1702 may be divided into two devices, such as a receiving circuit and a transmitting circuit. In some embodiments of the present application, the apparatus 1700 may further include an input device, a memory, and / or other components.

[0183] In some embodiments of the present application, the apparatus 1700 may be a BS. The processor 1706 may interact with other elements of the apparatus 1700 (e.g., the transceiver 1702, the DU, or the CU) to perform operations related to the BS, IAB donor, IAB donor CU, or IAB donor DU described in Figures 1-16. In some embodiments of the present application, the apparatus 1700 may be a network node. The transceiver 1702 and the processor 1706 may interact with each other to perform operations related to the network node or IAB node (mobile or stationary) described in Figures 1-16.

[0184] In some embodiments of the present application, the apparatus 1700 may further include at least one non-transitory computer-readable medium.

[0185] In some embodiments of the present disclosure, a non-transitory computer-readable medium may store computer-executable instructions that cause the processor 1706 to implement a method related to a BS, an IAB donor, an IAB donor CU, or an IAB donor DU, as described above. For example, the computer-executable instructions, when executed, cause the processor 1706, interacting with, for example, the transceiver 1702, to perform operations related to a BS, an IAB donor, an IAB donor CU, or an IAB donor DU, as described in FIGS. 1-16.

[0186] For example, in some embodiments of the present disclosure, a non-transitory computer-readable medium may store computer-executable instructions that cause the processor 1706 to implement methods related to a network node or IAB node (mobile or stationary) as described above. For example, the computer-executable instructions, when executed, cause the processor 1706 interacting with the transceiver 1702 to perform operations related to a network node or IAB node (mobile or stationary) described in FIGS. 1-16.

[0187] Those skilled in the art will understand that the operations or steps of a method described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the operations or steps of a method may reside as one or any combination or set of codes and / or instructions on a non-transitory computer-readable medium, which may be incorporated into a computer program product.

[0188] While the present disclosure has been described using specific embodiments thereof, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be exchanged, added, or substituted in other embodiments. Also, not all elements in the figures are necessary for the operation of the disclosed embodiments. For example, one skilled in the art of the disclosed embodiments would be able to make and use the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the present disclosure described herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0189] In this document, the terms "handover," "path switch," and "migration" may be used interchangeably. The terms "includes," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements, but may include other elements not specifically listed or inherent in such process, method, article, or apparatus. An element preceded by "a," "an," etc., does not, without further constraints, preclude the presence of additional identical elements in a process, method, article, or apparatus that includes that element. Also, the term "another" is defined as at least a second or more. Terms such as "having," as used herein, are defined as "including." Phrases such as "A and / or B" or "at least one of A and B" may include any and all combinations of the words listed with that phrase. For example, the phrase "A and / or B" or "at least one of A and B" may include A, B, or both A and B. Phrases such as "first," "second," etc. are used only to clarify embodiments of the present application, but are not used to limit the content of the present application. [Explanation of symbols]

[0190] 100 Wireless Communication System 110A, 110B IAB donor 120A, 120B, 120C IAB nodes 130A, 130B UE 140A, 140B, 140C, 140D Wireless Link 150A, 150B wireless link 200 User Plane (UP) Protocol Stack 300 Control Plane (CP) Protocol Stack 410A, 410B, 410C IAB donors 420A, 420B, 420C, 420D IAB nodes 430 UE 440A, 440B Signaling Flow 451 MT 452 MT 453 MT 454 MT 461 DU 462 DU 463 DU 464 DU 465 DU 466 DU 467 DU 475 CU 476 CU 477 CU 510A, 510B, 510C IAB donors 520A, 520B, 520C, 520D IAB nodes 530 UE 540A, 540B Signaling Flow 551 MT 552 MT 553 MT 554 MT 561 DU 562 DU 563 DU 564a, 564b DU 565 DU 566 DU 567 DU 575 CU 576 CU 577 CU 600 steps 610A, 610B, 610C BS 620 network nodes 700 steps 710A, 710B, 710C BS 720 network nodes 800A, 800B Procedure 810A, 810B BS 900 steps 910A, 910B BS 1000 steps 1010A, 1010B BS 1020 network nodes 1100 steps 1110A, 1110B, 1110C BS 1120 Network Node 1200 steps 1300 steps 1400 steps 1500 steps 1600 steps 1700 equipment 1702 Transceiver 1706 processor

Claims

1. a first base station (BS), A transceiver; a processor coupled to the transceiver, the processor comprising: determining whether there is an Internet Protocol (IP) connection between a second BS and a third BS, wherein one of the first BS and the second BS has a Radio Resource Control (RRC) connection to a Mobile Termination (MT) of a wireless network node, and the other of the first BS and the second BS has an Fl connection to a Distributed Unit (DU) of the wireless network node; Initiating a transition of the MT of the wireless network node to the third BS or a transition of the DU of the wireless network node to the third BS based on the determination. a first BS configured to:

2. To determine whether there is an IP connection between the second BS and the third BS, the processor: initiate a query to the second BS, the third BS, or both as to whether there is IP connectivity between the second BS and the third BS; determining whether there is IP connectivity between the second BS and the third BS based on a response to the inquiry from the second BS, the third BS, or both; The first BS of claim 1 , configured to:

3. 2. The first BS of claim 1, wherein the transceiver is configured to receive location information of the MT of the wireless network node from the wireless network node or the second BS to assist the first BS in initiating the migration of the DU of the wireless network node.

4. the transceiver is configured to receive, from the second BS, first information regarding IP connectivity to the second BS; the determination of whether there is IP connectivity between the second BS and the third BS is based on the first information; The first BS according to claim 1.

5. the transceiver is configured to transmit, to the second BS, second information regarding IP connectivity to the first BS; the second information is transmitted in response to the reception of the first information, or the first information is received in response to the transmission of the second information; The first BS according to claim 4.

6. 6. The first BS of claim 5, wherein the first information includes a first list of BSs, each BS in the first list of BSs having IP connectivity to the second BS, and the second information includes a second list of BSs, each BS in the second list of BSs having IP connectivity to the first BS.

7. a second base station (BS), a processor; a transceiver coupled to the processor, the transceiver comprising: receiving, from a first BS, second information regarding Internet Protocol (IP) connectivity to the first BS or an inquiry about IP connectivity of the second BS, wherein one of the first BS and the second BS has a Radio Resource Control (RRC) connection to a Mobile Termination (MT) of a wireless network node, and the other of the first BS and the second BS has an Fl connection to a Distributed Unit (DU) of the wireless network node; sending, to the first BS, first information regarding IP connectivity to the second BS; a second BS configured to:

8. 8. The second BS of claim 7, wherein the first information is transmitted in response to the inquiry, the inquiry being about whether there is IP connectivity between the second BS and a third BS, and the first information indicates IP connectivity between the second BS and the third BS.

9. 8. The second BS of claim 7, wherein the transceiver is further configured to transmit location information of the MT of the wireless network node to the first BS when the second BS has an RRC connection to the MT of the wireless network node.

10. 8. The second BS of claim 7, wherein the first information is transmitted in response to the reception of the second information or the second information is received in response to the transmission of the first information.

11. 1. A wireless network node, comprising: a processor; a transceiver coupled to the processor, the transceiver comprising: transmitting a request to a first base station (BS) to trigger a transition of a distributed unit (DU) of the wireless network node from the first BS to a third BS, the mobile termination (MT) of the wireless network node having a radio resource control (RRC) connection to a second BS; receiving a response in response to said request; a wireless network node configured to:

12. If the response confirms the request, the transceiver: In response to the receiving of the response, transmitting to the first BS a message indicating completion of an F1 interface setup between the wireless network node and the third BS.

12. The wireless network node of claim 11, configured to:

13. The wireless network node of claim 12 , wherein the message includes an identifier of the third BS.

14. The wireless network node of claim 11 , wherein the request includes an identifier of the first BS.

15. 12. The wireless network node of claim 11, wherein the transceiver is further configured to send a query to the second BS regarding whether there is an Internet Protocol (IP) connection between the second BS and the third BS, and wherein the sending of the request is based on a response to the query from the second BS.

Images