Method and device for communication in IAB network

Abstract

The embodiment of the invention relates to a method and equipment for communicating in an integrated access and backhaul (IAB) network. In accordance with some embodiments of the present disclosure, a first base station (BS) may: receive a transport migration management (TMM) request message from a second BS, where the TMM request message may include an identifier associated with a wireless network node for the first BS to identify the wireless network node; and transmitting a TMM response message to the second BS in response to receiving the TMM request message, in which a mobile terminal (MT) of the wireless network node switches from a third BS to the first BS and a distributed unit (DU) of the wireless network node has an F1 connection to the second BS, or in which the DU of the wireless network node migrates from a fourth BS to the second BS, and the MT of the wireless network node has a radio resource control (RRC) connection to the first BS.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to communication techniques, and more particularly to communicating in an integrated access and backhaul (IAB) network. Background Art

[0002] Wireless communication systems are widely deployed to provide various telecommunication services, such as telephony, video, data, messaging, and broadcasts. 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 include fourth-generation (4G) systems, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), or LTE-A Pro systems, and fifth-generation (5G) systems, which may also be referred to as New Radio (NR) systems.

[0003] In order to expand the coverage and availability of wireless communication systems (e.g., 5G systems), the Third Generation Partnership Project (3GPP) is envisioning an integrated access and backhaul (IAB) architecture for supporting multi-hop relays. In an IAB network, an IAB node may hop through one or more IAB nodes (also referred to as "IAB hosts" or "host nodes") before reaching a base station. A single hop can be considered a special case of multi-hop. Multi-hop backhaul is beneficial because it provides a relatively large coverage extension compared to a single-hop backhaul. In relatively high-frequency radio communication systems (e.g., radio signals transmitted in frequency bands exceeding 6 GHz), relatively narrow or small signal coverage may benefit from multi-hop backhaul technology.

[0004] The industry expects technologies to facilitate communications within the IAB Network. Summary of the Invention

[0005] Some embodiments of the present disclosure provide a first base station (BS). The first BS may include a processor; and a transceiver coupled to the processor. The transceiver may be configured to: receive a transport migration management (TMM) request message from a second BS, wherein the TMM request message may include an identifier associated with a radio network node for the first BS to identify the radio network node; and transmit a TMM response message to the second BS in response to receiving the TMM request message, wherein a mobile terminal (MT) of the radio network node is handed over from a third BS to the first BS, and a distributed unit (DU) of the radio network node has an F1 connection to the second BS, or wherein the DU of the radio network node migrates from a fourth BS to the second BS, and the MT of the radio network node has a radio resource control (RRC) connection to the first BS.

[0006] In some embodiments of the present disclosure, the identifier associated with the radio network node may include one of the following: a cell radio network temporary identifier (C-RNTI) of the MT of the radio network node, a BS-DU identifier (ID) of the DU of the radio network node, a backhaul adaptation protocol (BAP) address of the radio network node, a user equipment (UE) Xn application protocol (XnAP) ID of the MT of the radio network node, and a BS-DU UE F1 application protocol (F1AP) ID of the DU of the radio network node.

[0007] In some embodiments of the present disclosure, the TMM request message may include an information element (IE) indicating the identifier associated with the radio network node, and the IE is different from the non-F1-terminated BS UE XnAPID IE in the TMM request message. In some embodiments of the present disclosure, the processor may be configured to ignore the non-F1-terminated BS UE XnAPID IE in the TMM request message.

[0008] In some embodiments of the present disclosure, the processor may be further configured to allocate a UE XnAP ID of the MT of the wireless network node for use on the Xn interface between the first BS and the second BS in response to receiving the TMM request message, and the TMM response message may include the allocated UE XnAP ID.

[0009] In some embodiments of the present disclosure, the identifier associated with the radio network node may include a UE XnAPID of the MT of the radio network node to be used on an Xn interface between the first BS and the second BS.

[0010] In some embodiments of the present disclosure, the identifier associated with the radio network node is included in a non-F1 terminating BS UE XnAPID IE in the TMM request message.

[0011] In some embodiments of the present disclosure, the processor may be configured to allocate the UE XnAP ID of the MT of the wireless network node for use on the Xn interface between the first BS and the second BS, and wherein the transceiver is further configured to transmit the allocated UE XnAP ID to the third BS or the wireless network node.

[0012] In some embodiments of the present disclosure, the transceiver may be further configured to receive a request message for the UE XnAP ID from the third BS or the wireless network node, and wherein allocating the UE XnAP ID may include allocating the UE XnAP ID in response to receiving the request message.

[0013] In some embodiments of the present disclosure, the request message is a handover request message from the third BS, and the allocated UE XnAP ID is transmitted in a handover request confirm message.

[0014] In some embodiments of the present disclosure, the request message from the third BS may include an identifier of the second BS and the identifier associated with the radio network node; or wherein the request message from the radio network node may include the identifier of the second BS.

[0015] In some embodiments of the present disclosure, during the migration of the DU of the radio network node from the fourth BS to the second BS, the radio network node may include a first DU having an F1 connection to the fourth BS and a second DU having an F1 connection to the second BS. The BS-DUID of the DU of the radio network node is the BS-DUID of the first DU of the radio network node, and the BS-DU UE F1APID of the DU of the radio network node is the BS-DU UE F1APID of the first DU of the radio network node.

[0016] Some embodiments of the present disclosure provide a second base station (BS). The second BS may include a processor; and a transceiver coupled to the processor. The transceiver may be configured to: transmit a TMM request message to a first BS, wherein the TMM request message may include an identifier associated with a radio network node for the first BS to identify the radio network node; and receive a TMM response message from the first BS in response to transmitting the TMM request message, wherein a mobile operator (MT) of the radio network node is handed over from a third BS to the first BS and a DU of the radio network node has an F1 connection to the second BS, or wherein the DU of the radio network node is migrated from a fourth BS to the second BS and the MT of the radio network node has an RRC connection to the first BS.

[0017] In some embodiments of the present disclosure, the transceiver may be further configured to receive the identifier associated with the radio network node from the third BS. The identifier associated with the radio network node may include one of the following: a C-RNTI of the mobile terminal of the radio network node, a BS-DUID of the DU of the radio network node, a BAP address of the radio network node, and a UE XnAP ID of the mobile terminal of the radio network node.

[0018] In some embodiments of the present disclosure, the transceiver may be further configured to receive the identifier associated with the radio network node from the radio network node. The identifier associated with the radio network node may include one of the following: a C-RNTI of the MT of the radio network node, a BS-DUID of the DU of the radio network node, a BAP address of the radio network node, a UE XnAPID of the MT of the radio network node, and a BS-DU UE F1APID of the DU of the radio network node.

[0019] In some embodiments of the present disclosure, the TMM request message may include an IE indicating the identifier associated with the radio network node, and the IE is different from the non-F1 terminating BS UE XnAPIDIE in the TMM request message.

[0020] In some embodiments of the present disclosure, the processor may be configured to set the non-F1 terminating BS UE XnAPID IE in the TMM request message to be invalid or disabled.

[0021] In some embodiments of the present disclosure, the TMM response message may include a UE XnAP ID allocated by the first BS to the MT of the radio network node for use on an Xn interface between the first BS and the second BS.

[0022] In some embodiments of the present disclosure, the processor may be further configured to store the UE XnAPID allocated by the first BS.

[0023] In some embodiments of the present disclosure, the identifier associated with the radio network node may include a UE XnAP ID allocated by the first BS to the MT of the radio network node for use on an Xn interface between the first BS and the second BS.

[0024] In some embodiments of the present disclosure, the identifier associated with the radio network node is included in a non-F1 terminating BS UE XnAPIDIE in the TMM request message.

[0025] In some embodiments of the present disclosure, the identifier associated with the radio network node is received in an F1 Setup Request message.

[0026] In some embodiments of the present disclosure, during the migration of the DU of the radio network node from the fourth BS to the second BS, the radio network node may include a first DU having an F1 connection to the fourth BS and a second DU having an F1 connection to the second BS. The BS-DUID of the DU of the radio network node is the BS-DUID of the first DU of the radio network node, and the BS-DU UE F1APID of the DU of the radio network node is the BS-DU UE F1APID of the first DU of the radio network node.

[0027] Some embodiments of the present disclosure provide a method performed by a first base station (BS). The method may include: receiving a TMM request message from a second BS, wherein the TMM request message may include an identifier associated with a radio network node for the first BS to identify the radio network node; and transmitting a TMM response message to the second BS in response to receiving the TMM request message, wherein a mobile operator (MT) of the radio network node is handed over from a third BS to the first BS and a DU of the radio network node has an F1 connection to the second BS, or wherein the DU of the radio network node is migrated from a fourth BS to the second BS and the MT of the radio network node has an RRC connection to the first BS.

[0028] Some embodiments of the present disclosure provide a method performed by a second base station (BS). The method may include: transmitting a TMM request message to a first base station (BS), wherein the TMM request message may include an identifier associated with a radio network node for the first base station to identify the radio network node; and receiving a TMM response message from the first base station in response to transmitting the TMM request message, wherein a mobile operator (MT) of the radio network node is handed over from a third base station (BS) to the first base station (BS) and a user unit (DU) of the radio network node has an F1 connection to the second base station (BS), or wherein the DU of the radio network node is migrated from a fourth base station (BS) to the second base station (BS) and the mobile operator (MT) of the radio network node has an RRC connection to the first base station (BS).

[0029] 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 having computer-executable instructions stored thereon; at least one receiving circuitry; at least one transmitting circuitry; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry, and the at least one transmitting circuitry, wherein the at least one non-transitory computer-readable medium and the computer-executable instructions may be configured to cause the apparatus to perform methods according to some embodiments of the present disclosure using the at least one processor.

[0030] Embodiments of the present disclosure provide technical solutions that facilitate and improve the implementation of various communication technologies (e.g., 5G NR). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To illustrate the manner in which the advantages and features of the present disclosure can be obtained, the description of the present disclosure is presented by reference to specific embodiments of the disclosure illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the disclosure and therefore should not be considered limiting of its scope.

[0032] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure;

[0033] Figure 2A and 2B An example block diagram illustrating a protocol stack for an IAB network according to some embodiments of the present disclosure;

[0034] Figure 3 and 4 Describe exemplary switching scenarios according to some embodiments of the present disclosure;

[0035] Figure 5 Describe exemplary migration scenarios according to some embodiments of the present disclosure;

[0036] Figure 6 a flow chart illustrating an exemplary transport migration management (TMM) process according to some embodiments of the present disclosure;

[0037] Figure 7 and 8 A flowchart illustrating an exemplary handover process according to some embodiments of the present disclosure;

[0038] Figure 9 and 10 A flowchart illustrating an exemplary migration process according to some embodiments of the present disclosure;

[0039] Figure 11 and 12a flowchart illustrating an exemplary process for wireless communication according to some embodiments of the present disclosure; and

[0040] Figure 13 A block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0041] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments intended to be included in the spirit and scope of the present disclosure.

[0042] Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, the embodiments are provided in the context of specific network architectures and new service scenarios, such as 3rd Generation Partnership Project (3GPP) 5G (NR) and 3GPP Long Term Evolution (LTE) Release 8. It is contemplated that as network architectures and new service scenarios evolve, all embodiments of the present disclosure are also applicable to similar technical issues. Furthermore, the terminology used in the present disclosure may be modified without affecting the principles of the present disclosure.

[0043] Compared with 4G communication systems, 5G communication systems have put forward more stringent requirements for various network performance indicators, such as 1000-fold capacity increase, wider coverage requirements, ultra-high reliability, ultra-low latency, etc. Considering the abundant frequency resources of high-frequency carriers, in order to meet the ultra-high capacity requirements of 5G, the use of high-frequency small base station deployment in hot spots has become increasingly popular. However, high-frequency carriers have poor propagation characteristics, severe attenuation due to obstacles, and limited coverage. Therefore, dense deployment of small base stations is required. In addition, for these small base stations, the deployment of optical fiber may be difficult and expensive. Therefore, an economical and convenient backhaul solution is needed. Integrated access and backhaul (IAB) technology (whose access link and backhaul link can use wireless transmission solutions to avoid optical fiber deployment) provides ideas for solving the above problems.

[0044] In an IAB network, a radio network node, such as a relay node (RN), an IAB node, or a wireless backhaul node / device, can provide wireless access services to a UE. For example, a UE can connect to an IAB host relayed by one or more IAB nodes. An IAB host can also be referred to as a host node or host base station (e.g., DgNB, host gNodeB). In addition, a wireless link between an IAB host and an IAB node, or a wireless link between different IAB nodes, can be referred to as a "backhaul link." Radio network nodes in an IAB network can be fixed or mobile. Embodiments of the present disclosure can be applied to radio network nodes, regardless of whether they are fixed or mobile.

[0045] An IAB node may include an IAB mobile terminal (MT) and an IAB distributed unit (DU). When an IAB node is connected to its parent node (which may be another IAB node or an IAB host), it is considered a UE, acting as an MT. When an IAB node provides services to its child nodes (which may be another IAB node or a UE), it is considered a network device, acting as a DU.

[0046] The IAB host can be an access network element with complete base station functionality, or an access network element with separate centralized units (CUs) and distributed units (DUs). The IAB host can be connected to the core network (for example, to the 5G core (5GC) network) and provide wireless backhaul functionality for the IAB node. The CU of the IAB host can be referred to as an "IAB host-CU" (or simply "CU"), and the DU in the IAB host can be referred to as an "IAB host-DU". The IAB host-CU can be divided into a control plane (CP) and a user plane (UP). For example, the CU can include one CU-CP and one or more CU-UPs.

[0047] Considering the limited coverage of high-frequency bands and to ensure network coverage performance, multi-hop networking can be adopted in IAB networks. Considering the requirement for service transmission reliability, IAB nodes can support dual connectivity (DC) or multi-connectivity to improve transmission reliability and handle abnormal conditions that may occur on the backhaul (BH) link, such as radio link failure (RLF) or congestion, load fluctuations, etc.

[0048] In the case where the IAB network supports multi-hop and dual-connectivity networking, multiple transmission paths may exist between the UE and the IAB Host. The transmission path may include multiple nodes, such as the UE, one or more IAB nodes, and the IAB Host (if the IAB Host is in the form of separate CUs and DUs, it may also include IAB Host-DUs and IAB Host-CUs). Each IAB node may consider the neighboring node that provides backhaul services to it 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.

[0049] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present disclosure.

[0050] like Figure 1 As shown in FIG, the wireless communication system 100 may include some base stations (e.g., IAB host 110A and IAB host 110B), some IAB nodes (e.g., IAB node 120A, IAB node 120B, and IAB node 120C), and some UEs (e.g., UE 130A and UE 130B). Figure 1A specific number of UEs, IAB nodes, and IAB hosts are depicted in FIG. 1 , but it is contemplated that any number of UEs, IAB nodes, and IAB hosts may be included in the wireless communication system 100 .

[0051] According to some other embodiments of the present disclosure, each of the IAB host 110A, the IAB host 110B, the IAB node 120A, the IAB node 120B, and the IAB node 120C may be directly connected to one or more IAB nodes. According to some other embodiments of the present disclosure, each of the IAB host 110A, the IAB host 110B, the IAB node 120A, the IAB node 120B, and the IAB node 120C may be directly connected to one or more UEs.

[0052] UE 130A and UE 130B may be any type of device configured to operate and / or communicate in a wireless environment. For example, UE 130A and UE 130B may include computing devices such as desktop computers, laptop computers, personal digital assistants (PDAs), tablet computers, smart TVs (e.g., TVs connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle-mounted computers, network devices (e.g., routers, switches, and modems), etc. According to some embodiments of the present disclosure, UE 130A and UE 130B may include portable wireless communication devices, smartphones, cellular phones, flip phones, devices with subscriber identity modules, personal computers, selective call receivers, or any other device capable of transmitting and receiving communication signals over a wireless network. In some embodiments of the present disclosure, UE 130A and UE 130B may include wearable devices such as smart watches, fitness bands, optical head-mounted displays, Internet of Things (IoT) devices, etc. Furthermore, UE 130A and UE 130B may be referred to as subscriber units, mobile devices, mobile stations, users, terminals, mobile terminals, wireless terminals, fixed terminals, subscriber stations, user terminals or devices, or using other terminology used in the art.

[0053] The IAB hosts 110A and 110B can communicate with the core network ( Figure 1 The core network (CN) may include multiple core network components, such as the mobility management entity (MME) ( Figure 1 not shown) or Access and Mobility Management Function (AMF) ( Figure 1 The CN may serve as a gateway for the UE to access the Public Switched Telephone Network (PSTN) and / or other networks ( Figure 1 gateway (not shown).

[0054] 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 wireless communication networks, cellular telephone networks, time division multiple access (TDMA)-based networks, code division multiple access (CDMA)-based networks, orthogonal frequency division multiple access (OFDMA)-based networks, LTE networks, 3GPP-based networks, 3GPP 5G networks, satellite communication networks, high altitude platform networks, and / or other communication networks.

[0055] In some embodiments of the present disclosure, the wireless communication system 100 is compatible with the 5G NR of the 3GPP protocol. For example, the IAB hosts 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 on the UL using a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) or a cyclic prefix-OFDM (CP-OFDM) scheme. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0056] It should be understood by those skilled in the art 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.

[0057] refer to Figure 1 , IAB node 120A can be directly connected to IAB hosts 110A and 110B, and IAB node 120B can be directly connected to IAB host 110A. IAB hosts 110A and 110B are parent nodes of IAB node 120A, and IAB host 110A is the parent node of IAB node 120B. In other words, IAB nodes 120A and 120B are child IAB nodes of IAB host 110A, and IAB node 120A is also a child IAB node of IAB host 110B. IAB node 120C can reach IAB host 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 the child IAB node of IAB node 120B.

[0058] In some other embodiments of the present disclosure, the IAB node may be connected to the IAB node 120C, so it can reach the IAB host 110A by hopping through the IAB node 120C and the IAB node 120B. Such IAB node and the IAB node 120C may be referred to as descendant IAB nodes of the IAB node 120B.

[0059] UEs 130A and 130B may be connected to IAB nodes 120A and 120C, respectively. Therefore, 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 host (e.g., IAB host 110A or 110B) via one or more IAB nodes, and then transmitted by the IAB host to a mobile gateway device (e.g., a user plane function (UPF) in a 5GC). Downlink (DL) packets (e.g., data or signaling) may be transmitted from an IAB host (e.g., IAB host 110A or 110B) after being received by a gateway device, and then transmitted to UE 130A or 130B via one or more IAB nodes.

[0060] For example, reference Figure 1 UE 130A may transmit UL data to or receive DL data from IAB host 110A or 110B via IAB node 120A. UE 130B may transmit UL data to or receive DL data from IAB host 110A via IAB node 120C and IAB node 120B.

[0061] In an IAB deployment such as the wireless communication system 100, an IAB host (e.g., Figure 1 A radio link between an IAB host (e.g., an IAB host 110A or 110B) and an IAB node or between two IAB nodes may be referred to as a backhaul link (BL). Figure 1 The radio link between the IAB host 110A or 110B in the system and the UE or between the IAB node and the UE may be referred to as an access link (AL). Figure 1 , radio links 140A to 140D are BL, and radio links 150A and 150B are AL.

[0062] A protocol layer (Backhaul Adaptation Protocol (BAP) layer) located above the Radio Link Control (RLC) layer is introduced into the IAB system and can be used to implement packet routing, bearer mapping, and flow control on wireless backhaul links.

[0063] An F1 interface may be established between an IAB node (e.g., the DU portion of the IAB node) and an IAB host (e.g., the IAB host-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 Transmission Protocol (SCTP), IP, and other protocols.

[0064] Through the control plane of the F1 interface, the IAB node and IAB host can perform functions such as interface management, IAB-DU management, and UE context-related configuration. Through the user plane of the F1 interface, the IAB node and IAB host can perform functions such as user plane data transmission and downlink transmission status feedback.

[0065] Figure 2A An example block diagram illustrating a user plane (UP) protocol stack 200A for an IAB network according to some embodiments of the present disclosure. Figure 2B An example block diagram illustrating a control plane (CP) protocol stack 200B for an IAB network according to some embodiments of the present disclosure is shown. Figure 2A and 2B In the embodiment, the UE may be connected to the IAB host via the IAB node 2 and the IAB node 1. In some other embodiments of the present disclosure, the UE may be connected to the IAB host via more or fewer IAB nodes.

[0066] refer to Figure 2A The UP protocol stack of the UE may include the Service Data Adaptation Protocol (SDAP) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, the Medium Access Control (MAC) layer, and the Physical (PHY) layer. The UP protocol stack of the DU of IAB node 2 may include the GTP-U layer, the UDP layer, the IP layer, the RLC layer, the MAC layer, and the PHY layer. The UP protocol stack of the MT of IAB node 2 or the DU or MT of IAB node 1 may include the BAP layer, the RLC layer, the MAC layer, and the PHY layer. The UP protocol stack of the DU of the IAB host may include the IP layer, the BAP layer, the RLC layer, the MAC layer, and the PHY layer, wherein the PHY layer belongs to Layer 1 (L1), and the BAP layer, the RLC layer, and the MAC layer belong to Layer 2 (L2). The protocol stack of the CU-UP of the IAB host may include the GTP-U layer, the UDP layer, the IP layer, the SDAP layer, the PDCP layer, the L2 layer, and the L1 layer.

[0067] refer to Figure 2B, 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 the IAB node 2 may include a 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 the IAB node 2 or the DU or MT of the 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 host may include an IP layer, a BAP layer, an RLC layer, a MAC layer, and a PHY layer, wherein the PHY layer belongs to L1, and the BAP layer, RLC layer, and MAC layer belong to L2. The protocol stack of the CU-CP of the IAB host may include an RRC layer, a PDCP layer, an F1AP layer, an SCTP layer, an IP layer, an L2 layer, and an L1 layer.

[0068] Figure 2A and 2B The protocol stack shown in is for illustrative purposes only. For example, Figure 2A and 2B The sequence of some of the protocol layers in the protocol stack can be rearranged. For example, although the SDAP and PDCP layers belong to L2, in Figure 2A In FIG, it is shown above the GTP-U layer, UDP layer and IP layer in the protocol stack of the CU-UP hosted by the IAB.

[0069] The signals between each node in the IAB network may include, for example, the following, and may be applied to the present disclosure:

[0070] -IAB Host-CU and IAB Host-DU: F1AP message;

[0071] -IAB host - CU and IAB node: F1AP messages between CU and IAB-DU or RRC messages between CU and IAB-MT;

[0072] -IAB host-CU and UE: RRC message;

[0073] - Access IAB node and UE: L2-control PDUs, such as MAC Control Element (CE) or RLC Control PDUs; and

[0074] - IAB node and another child or parent IAB node: L2-control PDU, such as MAC CE, RLC control PDU or BAP control PDU.

[0075] As the demand for improved cellular coverage and connectivity continues to increase, communications in outdoor and mobile scenarios may face more challenges. In some embodiments of the present disclosure, a mobile radio network node that acts as a repeater between a UE and a 3GPP communication network (e.g., 5G) may be used to facilitate communications in such scenarios. The mobile radio network node may provide, for example, an access link to the UE and be wirelessly connected (e.g., using NR) to the core network through a BS (e.g., a host next generation radio access network (NG-RAN)). In some instances, such a mobile radio network node may also be referred to as a mobile base station repeater or a mobile repeater. The above description of radio network nodes and IAB nodes may be applied to mobile base station repeaters. That is, the mobile base station repeater may be a mobile IAB node.

[0076] In some examples, a mobile base station relay may be mounted on a vehicle. The mobile base station relay may serve UEs located inside (onboard) or outside (around) the vehicle, or UEs entering or leaving the vehicle. In the context of this disclosure, "inside" or "outside" a mobile base station relay may mean inside or outside a vehicle or other device on which the mobile wireless network node is mounted.

[0077] 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), which are different from UE relays (which use PC5-based links to provide, for example, indirect connections to remote UEs). 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.

[0078] The adoption of such mobile wireless network nodes is advantageous in various ways and can be applied in a variety of scenarios. For example, in some outdoor environments, the availability of vehicles equipped with mobile base station repeaters, either following a known / predictable itinerary (e.g., buses, trams, etc.) or located in convenient locations (e.g., outside stadiums, hotspots, or emergency locations), can provide opportunistic improvements to cellular coverage and capacity when and where needed. For example, those repeaters can utilize 5G wireless backhaul to the macro network and, therefore, provide better coverage and connectivity to neighboring UEs. Mobile repeaters are also well-suited for improving connectivity for users or devices inside the vehicle on which they are installed in various environments, such as passengers, specialized / professional personnel, or equipment on buses, cars / taxi, or trains. Such mobile wireless network nodes can also be used to reach users or devices that would otherwise have no or very poor macro coverage, for example, if first responders are displaced from their original location in an indoor building / area and can use repeaters placed nearby or on external vehicles to obtain the required coverage and connectivity.

[0079] The technical benefits of using such mobile wireless network nodes further include, among other things, the ability to obtain better macro coverage than nearby UEs, for example, by utilizing better radio frequency, antenna, and power capabilities. Furthermore, in addition to the value to network operators and end users, other parties, such as vehicle manufacturers, and vehicle and fleet owners or providers, may also find valuable incentives to install and operate repeaters in their vehicles.

[0080] In the context of this disclosure, a radio network node may refer to a fixed or mobile radio network node.

[0081] Due to the mobility of wireless network nodes (eg, IAB nodes), the wireless network nodes may need to migrate (or switch) from one IAB host to another IAB host (ie, inter-host migration).

[0082] In some embodiments, the MT of the wireless network node may migrate from the initial (source) IAB host to the new (target) IAB host. For example, the MT of the wireless network node may migrate to a different parent node under a different CU of the IAB host. For example, return to reference Figure 1, the MT of IAB node 120C or IAB node 120B may migrate from IAB host 110A to IAB host 110B. In this scenario, the DU of the radio network node and the DU of the descendant nodes of the radio network node may maintain F1 connectivity with the source IAB host (e.g., the CU of the source IAB host). This migration may be referred to as an inter-host partial migration or an inter-host IAB-MT handover. The radio network node that performs the inter-host partial migration may be referred to as a border radio network node. After the inter-host partial migration, the F1 traffic of the DU of the radio network node and the DU of the descendant nodes of the radio network node may be routed via, for example, the BAP layer of the IAB topology to which the MT of the radio network node has migrated.

[0083] In some embodiments, a DU of a radio network node may be migrated from an initial (source) IAB host to a new (target) IAB host. This migration may be referred to as an inter-host IAB-DU migration. In some embodiments, to perform handover of a UE served by a radio network node (e.g., its DU), the radio network node may simultaneously support two logical DUs (e.g., DU#1 and DU#2), which may have F1AP associations with a source IAB host (e.g., a CU of the source IAB host) and a target IAB host (e.g., a CU of the target IAB host), respectively. A UE connected to the radio network node may be handed over from the cell of DU#1 (i.e., the source DU of the radio network node) to the cell of DU#2 (i.e., the target DU of the radio network node). After the migration of the DU of the radio network node, the F1 interface between DU#1 and the source IAB host may be released.

[0084] In the context of this disclosure, the terms handover and migration are used interchangeably. It should be noted that although the embodiments of the present disclosure may be discussed in the context of a specific network architecture (e.g., an IAB architecture) and based on certain specific components (e.g., an IAB host or an IAB node), the embodiments of the present disclosure are also applicable to other similar network architectures and new service scenarios. It should be noted that although in the context of this disclosure, both a BS (e.g., an IAB host) and a network node (e.g., an IAB node) may include a DU, the DU of the BS and the DU of the network node generally function differently.

[0085] For example, Figure 3 Shows exemplary switching scenarios according to some embodiments of the present disclosure. Figure 3, the IAB host 310A may include IAB-host-CU1 and IAB-host-DU1, and the IAB host 310B may include IAB-host-CU2 and IAB-host-DU2. The IAB node 321 may be connected to the IAB host 310A and may include IAB-MT 1 and IAB-DU 1, and the IAB node 322 may be connected to the IAB host 310B and may include IAB-MT 2 and IAB-DU 2. The IAB node 323 may include IAB-MT 3 and IAB-DU 3. The details described in all the above embodiments of the present disclosure apply to Figure 3 .

[0086] exist Figure 3 In the example of FIG, the MT (IAB-MT 3) of the IAB node 323 may be switched from IAB-Host-CU1 to IAB-Host-CU2. Before the switching of the IAB node 323, the IAB node 323 may reach the IAB host 310A via the IAB node 321. Both the IAB-MT 3 and the IAB-DU 3 may be anchored at the IAB-Host-CU1. During the switching of the IAB-MT 3, the F1 transmission between the IAB-DU 3 and the IAB host 310A (e.g., IAB-Host-CU1) is switched from the source path ( Figure 3 3 (not shown) switches to a target path (represented by signaling flow 330) under the topology of the IAB host 310B (eg, IAB-Host-CU2).

[0087] After the IAB node 323 is switched, the IAB-MT 3 may be switched from the IAB host 310A to the IAB host 310B, and the IAB-DU 3 may remain under the control of the IAB-host-CU1. That is, after the MT switch, the IAB-MT 3 may be anchored at the IAB-host-CU2, and the IAB-DU 3 may still be anchored at the IAB-host-CU1. The IAB-host-CU1 may be referred to as the "F1-terminating CU." The IAB-host-CU2 may be referred to as the "non-F1-terminating CU" or the "RRC-terminating CU." The IAB host 310A may be referred to as the "F1-terminating IAB host" or the "F1-terminating BS." The IAB host 310B may be referred to as the "non-F1-terminating IAB host," the "non-F1-terminating BS," or the "RRC-terminating BS."

[0088] Figure 4 Shows exemplary switching situations according to some other embodiments of the present disclosure. Figure 4In the example of , the MT of the radio network node is handed over from the BS to another BS, while the DU of the radio network node is connected to yet another BS (hereinafter, "Scenario 1"). The details described in all the above embodiments of the present disclosure are applicable to Figure 4 .

[0089] refer to Figure 4 , IAB host 410A may include CU 475 and DU 465, IAB host 410B may include CU 476 and DU 466, and IAB host 410C may include CU 477 and DU 467. IAB node 420A may be directly connected to IAB host 410A and may include MT 451 and DU 461. IAB node 420B may be directly connected to IAB host 410B and may include MT 452 and DU 462. IAB node 420C may be directly connected to IAB host 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 an access IAB node for UE 430.

[0090] DU 464 of IAB node 420D may be anchored at IAB host 410C (e.g., CU 477). IAB host 410C may be referred to as the F1-terminating BS of IAB node 420D. MT 454 of IAB node 420D may be switched (or migrated) from IAB host 410A (i.e., a source non-F1-terminating BS) to IAB host 410B (i.e., a target non-F1-terminating BS). During the handover of MT 454, F1 transmission between DU 464 and IAB host 410C switches from the topology of IAB host 410A (e.g., represented by signaling flow 440A) to the topology of IAB host 410B (e.g., represented by signaling flow 440B).

[0091] Figure 5 Demonstrating exemplary migration scenarios according to some embodiments of the present disclosure. Figure 5 In the example of , the DU of the radio network node migrates from a BS to another BS, while the MT of the radio network node is connected to yet another BS (hereinafter, "Scenario 2"). The details described in all the above embodiments of the present disclosure are applicable to Figure 5 .

[0092] refer to Figure 5, IAB host 510A may include CU 575 and DU 565, IAB host 510B may include CU 576 and DU 566, and IAB host 510C may include CU 577 and DU 567. IAB node 520A may be directly connected to IAB host 510A and may include MT 551 and DU 561. IAB node 520B may be directly connected to IAB host 510B and may include MT 552 and DU 562. IAB node 520C may be directly connected to IAB host 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 the access IAB node of UE 530.

[0093] MT 554 of IAB node 520D may be anchored at IAB host 510B (e.g., CU 576). IAB host 510B may be referred to as a non-F1-terminating BS of IAB node 520D. DUs of IAB node 520D may be migrated from IAB host 510A (i.e., source F1-terminating BS) to IAB host 510C (i.e., target F1-terminating BS). Before DU migration, only DU 564a of IAB node 520D has an F1 connection to IAB host 510A (e.g., represented by signaling flow 540A). During DU migration, IAB node 520D may have two DUs (e.g., as Figure 5 DU 564a and DU 564b are shown in FIG. DU 564a may have an F1 connection to IAB host 510A, and DU 564b may have an F1 connection to IAB host 510C (e.g., as represented by signaling flow 540B). After DU migration, only DU 564b of IAB node 520D has an F1 connection to IAB host 510C. Both F1 connections are transported through the topology of IAB host 510B.

[0094] Figures 3 to 5 The MT handover and DU migration shown in FIG are for illustrative purposes only. For example, in some other embodiments, the MT and DU of the wireless network node may be anchored at the same BS (e.g., IAB host), and the DU of the wireless network node may be migrated from the source BS to the target BS (e.g., IAB host). 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 or target BS, or may be directly connected to the source or target BS.

[0095] Embodiments of the present disclosure provide solutions for facilitating handover or migration of wireless network nodes.

[0096] For example, in scenario 1, F1 terminates BS (e.g., Figure 4 The IAB host 410C in the embodiment may not be aware that the wireless network node has been transferred to a (target) non-F1 terminating BS (eg, Figure 4 and in scenario 2, (target) F1 terminates BS (eg, Figure 5 The IAB host 510C in FIG. 5 may not be aware of which node is the non-F1 terminating BS (eg, Figure 5 Embodiments of the present disclosure provide a solution for notifying an F1-terminating BS (or an F1-terminating CU) of the existence of a non-F1-terminating BS (or a non-F1-terminating CU), and a solution for associating wireless network nodes between the F1-terminating BS (or the F1-terminating CU) and the non-F1-terminating BS (or the non-F1-terminating CU).

[0097] For example, as described above, the MT and DU of a radio network node may be connected to different BSs (or CUs). In some embodiments of the present disclosure, a TMM procedure between two BSs (or CUs) may be performed to exchange information between the two BSs (or CUs) and to manage the migration of radio network node and subsequent radio network node services between the topologies managed by the two BSs (or CUs). In the context of an IAB network, the TMM procedure may also be referred to as an IAB TMM procedure.

[0098] For example, a TMM process may be performed between an F1-terminating BS (e.g., an F1-terminating IAB-host-CU) of a radio network node (e.g., an IAB node) and a non-F1-terminating BS (e.g., a non-F1-terminating IAB-host-CU) to exchange information and manage the migration of radio network node and descendant node traffic between topologies managed by the two BSs (e.g., two IAB-host-CUs). For example, the process may be initiated by the F1-terminating BS (e.g., an F1-terminating IAB-host-CU) of the IAB node. For example, the process may be used to set, modify, and release (e.g., for the purpose of revocation) resources under a non-F1-terminating BS (e.g., a non-F1-terminating IAB-host-CU) used to serve offloaded traffic.

[0099] Figure 6 A flowchart illustrating an exemplary TMM process 600 according to some embodiments of the present disclosure. Figure 6 For example, BSs 610A and 610B may serve as IAB hosts as described above and may include a CU and at least one DU.

[0100] BSs 610A and 610B may be an F1-terminated BS and a non-F1-terminated BS of a wireless network node (denoted as node #1 for clarity). For example, the DU of node #1 may have an F1 connection to BS 610A, and the MT of node #1 may have an RRC connection to BS 610B. In operation 621, BS 610A may transmit a TMM request message (e.g., an IAB TMM request message) to BS 610B. In operation 623, BS 610B may transmit a TMM response message (e.g., an IAB TMM response message) to BS 610A in response.

[0101] In some embodiments of the present disclosure, the TMM request message and the TMM response message may indicate the UE XnAPID (e.g., NG-RAN node UE XnAPID) allocated by both BS 610A and BS 610B for the MT of node #1 for use on the Xn interface between BS 610A and BS 610B. The two UE XnAPIDs may be included in the F1-terminated BS UE XnAPID IE and the non-F1-terminated BS UE XnAPID IE in the TMM request and TMM response messages, respectively.

[0102] UE XnAPID may be assigned by BS 610A and BS 610B. For example, the MT of node #1 may be handed over from BS 610A to BS 610B. For example, node #1 may perform the following Figure 3 . For example, the MT of node #1 may be handed over from BS 610A to BS 610B, while the DU of node #1 may still be under the control of BS 610A. During the handover of the MT of node #1 from BS 610A to BS 610B (e.g., during the IAB-MT handover preparation process), BS 610A (e.g., the CU of BS 610A) may allocate a UE XnAPID (denoted as "ID#1") to the MT of node #1, which may be included in the handover request message from BS 610A to BS 610B. BS 610B (e.g., the CU of BS 610B) may feedback the UE XnAPID (denoted as "ID#2") of the MT of node #1. For example, BS 610B may transmit a handover request confirmation message including ID#2 to BS 610A. The handover request confirmation message may also include ID#1. After the handover preparation process, BS 610A (e.g., CU of BS 610A) and BS 610B (e.g., CU of BS 610B) may have the UE XnAPID of the MT of Node #1 assigned by each other. After the handover of the MT of Node #1 from BS 610A to BS 610B, BS 610A (e.g., CU of BS 610A) may trigger the following Figure 6UE XnAPIDs (eg, ID#1 and ID#2) allocated by BS 610A (eg, the CU of BS 610A) and BS 610B (eg, the CU of BS 610B) may be included in the TMM request message and the TMM response message.

[0103] In scenarios 1 and 2 (e.g. Figure 4 and 5 ), after MT handover or DU migration, F1 terminates F1 signaling between the BS and the radio network node (e.g., Figure 4 F1 signaling between the IAB host 410C and the IAB node 420D or Figure 5 F1 signaling between the IAB host 510C and the IAB node 520D in the non-F1 terminating BS (e.g., Figure 4 IAB host 410B or Figure 5 Similarly, the F1 termination BS (e.g., Figure 4 IAB Host 410C or Figure 5 The IAB host 510C in the F1 terminal BS (eg, Figure 4 IAB host 410B or Figure 5 The IAB host 510B in the BS triggers the TMM process to exchange information and manage the migration of services between the two BSs (e.g., two CUs). However, in scenarios 1 and 2, the F1-terminated BS and the non-F1-terminated BS may not have yet allocated and exchanged UE XnAPIDs for the Xn interface between the F1-terminated BS and the non-F1-terminated BS. Embodiments of the present disclosure provide a solution for exchanging UE XnAPIDs for the Xn interface between the F1-terminated BS and the non-F1-terminated BS. For example, since the TMM process between the F1-terminated BS and the non-F1-terminated BS requires such an ID (e.g., the F1-terminated BS may trigger a TMM request containing the non-F1-terminated BS UE XnAP ID to the non-F1-terminated BS), embodiments of the present disclosure provide a solution for setting the non-F1-terminated BS UE XnAP ID in the TMM request message.

[0104] More details about the embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0105] For example, Figure 7 A flow chart illustrating an exemplary handover process 700 according to some embodiments of the present disclosure.

[0106] The details described in all the above embodiments of the present disclosure apply to Figure 7For example, BSs 710A to 710C may serve as IAB hosts as described above and may include a CU and at least one DU. Network node 720 may serve as an IAB node as described above and may include an MT and a DU.

[0107] Network node 720 (e.g., a DU of network node 720) may have an F1 connection with BS 710C (e.g., a CU of BS 710C). Network node 720 (e.g., an MT of network node 720) may have an RRC connection with BS 710A (e.g., a CU of BS 710A). BS 710C and BS 710A may be referred to as an F1-terminated BS and a non-F1-terminated BS (or an RRC-terminated BS), respectively. The CU of BS 710C and the CU of BS 710A may be referred to as an F1-terminated BS-CU and a non-F1-terminated BS-CU (or an RRC-terminated BS-CU), respectively.

[0108] In some embodiments, the MT of network node 720 may perform a handover from BS 710A (i.e., a source non-F1-terminating BS) to a target BS (i.e., a target non-F1-terminating BS, such as BS 710B), while the DU of network node 720 maintains its connection with BS 710C (e.g., a CU of BS 710C). For example, BS 710A, BS 710B, BS 710C, and network node 720 may function as Figure 4 The IAB host 410A, the IAB host 410B, the IAB host 410C and the IAB node 420D.

[0109] For example, reference Figure 7 In operation 711, a handover preparation procedure of the network node 720 (e.g., the MT of the network node 720) may be performed between the BS 710A and the BS 710B. For example, the BS 710A (e.g., the CU of the BS 710A) may transmit a handover request message to the BS 710B (e.g., the CU of the BS 710B) to handover the network node 720 (e.g., the MT of the network node 720). The BS 710B (e.g., the CU of the BS 710B) may transmit a response to the handover request message (e.g., positive feedback, such as a handover request confirmation message, or negative feedback, such as a handover preparation failure message) to the BS 710A.

[0110] In some embodiments, operation 711 may further include the following steps: BS 710B (e.g., the CU of BS 710B) sets up a UE context for network node 720 (e.g., the MT of network node 720) in the target parent node, performs admission control on network node 720 (e.g., the MT of network node 720), and provides an RRC reconfiguration (e.g., a handover command) as part of a handover request confirmation message.

[0111] In some embodiments, the handover request message may include a UE XnAP ID (e.g., an NG-RAN node UE XnAP ID, represented as ID#7A) assigned by BS 710A (e.g., the CU of BS 710A). The handover request confirmation message may include a UE XnAP ID (e.g., an NG-RAN node UE XnAP ID, represented as ID#7B) assigned by BS 710B (e.g., the CU of BS 710B). The handover request confirmation message may also include ID#7A. ID#7A and ID#7B may be used on the Xn interface between BS 710A (e.g., the CU of BS 710A) and BS 710B (e.g., the CU of BS 710B).

[0112] In operation 713, BS 710A (e.g., the CU of BS 710A) may transmit a handover command (e.g., RRC reconfiguration) to network node 720 (e.g., the MT of network node 720). In some embodiments, the handover command or RRC reconfiguration may be included in a UE context modification request message to a source parent node (e.g., the DU of the source parent node of network node 720). In some examples, it is assumed that network node 720 functions as Figure 4 4. In the example of FIG. 4, the source and target parent nodes of network node 720 may be IAB node 420D in FIG. 4, and IAB node 420B in FIG. 4. The source and target parent nodes of network node 720 may be IAB node 420A and IAB node 420B, respectively. The source parent node (e.g., the DU of the source parent node of network node 720) may forward the received handover command or RRC reconfiguration to the migrating node (e.g., the MT of network node 720). In some examples, the source or target parent node of network node 720 may be a BS or an IAB host.

[0113] In operation 715, the network node 720 (eg, the MT of the network node 720) may perform a random access procedure with the target parent node (eg, the DU of the target parent node of the network node 720) and set up an RRC connection to the BS 710B (eg, the CU of the BS 710B).

[0114] In operation 717, BS 710A (eg, the CU of BS 710A) may transmit a message to BS 710C (eg, the CU of BS 710C) to indicate that network node 720 (eg, the MT of network node 720) has switched to BS 710B (eg, the CU of BS 710B).

[0115] In some embodiments, the message in operation 717 may include an identifier of BS 710B (e.g., an ID of a CU of BS 710B) so that BS 710C (e.g., a CU of BS 710C) can trigger a TMM process to the correct non-F1 termination BS (e.g., a non-F1 termination CU, such as the CU of BS 710B). For example, the ID of BS 710B may be the gNB ID of BS 710B, the gNB-CU ID of the CU of BS 710B, the IP address of the CU of BS 710B, or any ID that can identify BS 710B (e.g., the CU of BS 710B).

[0116] In some embodiments, the message in operation 717 may include an identifier (ID) associated with network node 720. As will be described later, the ID associated with network node 720 may be used to allow BS 710B (e.g., a CU of BS 710B) to identify network node 720. That is, any ID associated with network node 720 known to BS 710B (e.g., a CU of BS 710B) may be employed.

[0117] For example, the ID associated with the network node 720 may be an ID of a MT of the network node 720, an ID of a DU of the network node 720, or an ID of the network node 720. For example, the ID associated with the network node 720 may be a cell radio network temporary identifier (C-RNTI) of the MT of the network node 720, a BS-DUID (e.g., gNB-DUID) of a DU of the network node 720, a BAP address of the network node 720, or a UE XnAP ID (e.g., NG-RAN node UE XnAP ID) of the MT of the network node 720. For example, the ID associated with the network node 720 may be a UE XnAP ID (e.g., ID#7B) allocated by the BS 710B to the MT of the network node 720 or a UE XnAP ID (e.g., ID#7A) allocated by the BS 710A to the MT of the network node 720.

[0118] BS 710C (e.g., the CU of BS 710C) may then trigger a TMM process (e.g., an IAB TMM process) to exchange information between BS 710C (e.g., the CU of BS 710C) and BS 710B (e.g., the CU of BS 710B) of network node 720 and manage the migration of network node 720 and descendant node traffic between the topologies managed by the two BSs (e.g., the two CUs). For example, in operation 719, BS 710C (e.g., the CU of BS 710C) may transmit a TMM request message to BS 710B (e.g., the CU of BS 710B).

[0119] In some embodiments, the TMM request message may include an ID associated with network node 720 , as described above with respect to operation 717 .

[0120] In some embodiments, the TMM request message may include a non-F1 terminating BS UE XnAPID IE (eg, a non-F1 terminating IAB-host UE XnAP ID IE). Figure 6 As described, the F1-terminating BS (e.g., BS 710C) should include the UE XnAPID (e.g., NG-RAN node UE XnAPID) of the MT of the radio network node (e.g., network node 720) in the non-F1-terminating BS UE XnAP ID IE, which is allocated by the non-F1-terminating BS (e.g., BS 710B) and is to be used on the Xn interface between the F1-terminating BS (e.g., BS 710C) and the non-F1-terminating BS (e.g., BS 710B). For example, the value of the IE is an ID, or the IE is set to an ID. However, in Figure 7 In the example, BS 710C (e.g., the CU of BS 710C) does not have information about such UE XnAPID at operation 717. BS 710C (e.g., the CU of BS 710C) may set the non-F1-terminated BS UE XnAPID IE in the TMM request message to be invalid or disabled. For example, BS 710C (e.g., the CU of BS 710C) may set the non-F1-terminated BS UE XnAPID IE using an invalid or disabled ID.

[0121] In some embodiments, an ID associated with the network node 720 may be included in an IE of the TMM request message that is different from the non-F1 terminating BS UE XnAP ID IE.

[0122] In some embodiments, the TMM request message may include an F1-terminating BS UE XnAPID IE (e.g., an F1-terminating IAB-host UE XnAP ID IE), which may include a UE XnAP ID (e.g., an NG-RAN node UE XnAPID) allocated by BS 710C (e.g., a CU of BS 710C) and to be used on the Xn interface between BS 710C and BS 710B. For example, the value of the F1-terminating BS UE XnAP ID IE may be the UE XnAP ID allocated by BS 710C, or the F1-terminating BS UE XnAPID IE may be set to the UE XnAPID allocated by BS 710C.

[0123] In some embodiments, BS 710B (e.g., the CU of BS 710B) may identify network node 720 based on the ID associated with network node 720 in the TMM request message. In some embodiments, BS 710B (e.g., the CU of BS 710B) may ignore the non-F1-terminated BS UE XnAP ID IE in the TMM request message. For example, when the TMM request message includes the ID associated with network node 720, BS 710B (e.g., the CU of BS 710B) may ignore the non-F1-terminated BS UE XnAP ID IE.

[0124] In some embodiments, BS 710B (e.g., the CU of BS 710B) may allocate a UE XnAP ID (e.g., an NG-RAN node UE XnAP ID) of the MT of network node 720 for use on the Xn interface between BS 710B and BS 710C in response to receiving the TMM request message. For example, when the TMM request message includes an ID associated with network node 720, BS 710B (e.g., the CU of BS 710B) may allocate a UE XnAP ID to the MT of network node 720.

[0125] In operation 721, BS 710B (e.g., the CU of BS 710B) may transmit a TMM response message to BS 710C (e.g., the CU of BS 710C) as a response to the TMM request message. In some embodiments, the TMM response message may include a UE XnAP ID assigned by BS 710B (e.g., the CU of BS 710B) for use on the Xn interface between the F1-terminating BS (e.g., BS 710C) and the non-F1-terminating BS (e.g., BS 710B). For example, BS 710B (e.g., the CU of BS 710B) may set the non-F1-terminating BS UE XnAP ID IE (e.g., the non-F1-terminating IAB-Host UE XnAP ID IE) in the TMM response message to the assigned UE XnAP ID. For example, the value of the non-F1-terminating BS UE XnAP ID IE in the TMM response message is the assigned UE XnAP ID.

[0126] In some embodiments, the TMM response message may also include an F1-terminating BS UE XnAP ID IE (eg, F1-terminating IAB-host UE XnAPID IE), which is set to the same value as the F1-terminating BS UE XnAP ID IE in the TMM request message.

[0127] In some embodiments, BS 710C (e.g., the CU of BS 710C) may store the UE XnAPID assigned by BS 710B (e.g., the CU of BS 710B) in response to receiving the TMM response message. For example, when the TMM request message contains an invalid / failed UE XnAPID (e.g., the non-F1-terminated BS UE XnAPID IE in the TMM request message is invalid or failed), BS 710C (e.g., the CU of BS 710C) may store the UE XnAPID in the non-F1-terminated BS UE XnAPID IE in the corresponding TMM response message.

[0128] After the above operations, BS 710B (e.g., the CU of BS 710B) and BS 710C (e.g., the CU of BS 710C) may have UE XnAPID allocated by each other for use on the Xn interface between BS 710B (e.g., the CU of BS 710B) and BS 710C (e.g., the CU of BS 710C).

[0129] After the TMM process, BS 710B (eg, the CU of BS 710B) may update the BAP configuration, and F1 traffic between network node 720 and BS 710C (eg, the CU of BS 710C) may be transmitted via the BH link under BS 710B (eg, the CU of BS 710B).

[0130] Those skilled in the art will appreciate that the sequence of operations in exemplary process 700 may be changed, and some of the operations in exemplary process 700 may be eliminated or modified, without departing from the spirit and scope of the present disclosure.

[0131] For example, Figure 8 A flow chart illustrating an exemplary handover process 800 according to some embodiments of the present disclosure.

[0132] The details described in all the above embodiments of the present disclosure apply to Figure 8 For example, BSs 810A to 810C may serve as IAB hosts as described above and may include a CU and at least one DU. Network node 820 may serve as an IAB node as described above and may include an MT and a DU.

[0133] Network node 820 (e.g., a DU of network node 820) may have an F1 connection with BS 810C (e.g., a CU of BS 810C). Network node 820 (e.g., an MT of network node 820) may have an RRC connection with BS 810A (e.g., a CU of BS 810A). BS 810C and BS 810A may be referred to as an F1-terminated BS and a non-F1-terminated BS (or an RRC-terminated BS), respectively. The CU of BS 810C and the CU of BS 810A may be referred to as an F1-terminated BS-CU and a non-F1-terminated BS-CU (or an RRC-terminated BS-CU), respectively.

[0134] In some embodiments, the MT of network node 820 may perform a handover from BS 810A (i.e., a source non-F1-terminating BS) to a target BS (i.e., a target non-F1-terminating BS, such as BS 810B), while the DU of network node 820 maintains its connection with BS 810C (e.g., a CU of BS 810C). For example, BS 810A, BS 810B, BS 810C, and network node 820 may function as Figure 4 The IAB host 410A, the IAB host 410B, the IAB host 410C and the IAB node 420D.

[0135] For example, reference Figure 8 In operation 811, a handover preparation procedure of the network node 820 (e.g., the MT of the network node 820) may be performed between the BS 810A and the BS 810B. For example, the BS 810A (e.g., the CU of the BS 810A) may transmit a handover request message to the BS 810B (e.g., the CU of the BS 810B) to handover the network node 820 (e.g., the MT of the network node 820). The BS 810B (e.g., the CU of the BS 810B) may transmit a response to the handover request message (e.g., positive feedback, such as a handover request confirmation message, or negative feedback, such as a handover preparation failure message) to the BS 810A.

[0136] In some embodiments, operation 811 may further include the following steps: BS 810B (e.g., the CU of BS 810B) sets up a UE context for network node 820 (e.g., the MT of network node 820) in the target parent node, performs admission control on network node 820 (e.g., the MT of network node 820), and provides an RRC reconfiguration (e.g., a handover command) as part of a handover request confirmation message.

[0137] In some embodiments, the handover request message may include a UE XnAP ID (e.g., an NG-RAN node UE XnAP ID, denoted as ID#8A) assigned by BS 810A (e.g., the CU of BS 810A). The handover request confirmation message may include a UE XnAP ID (e.g., an NG-RAN node UE XnAP ID, denoted as ID#8B) assigned by BS 810B (e.g., the CU of BS 810B). The handover request confirmation message may also include ID#8A. ID#8A and ID#8B may be used on the Xn interface between BS 810A (e.g., the CU of BS 810A) and BS 810B (e.g., the CU of BS 810B).

[0138] In operation 813, BS 810A (e.g., the CU of BS 810A) may transmit a handover command (e.g., RRC reconfiguration) to network node 820 (e.g., the MT of network node 820). In some embodiments, the handover command or RRC reconfiguration may be included in a UE context modification request message to a source parent node (e.g., the DU of the source parent node of network node 820). In some examples, it is assumed that network node 820 functions as Figure 4 4. In the example of FIG. 4, the source and target parent nodes of network node 820 may be IAB node 420A and IAB node 420B, respectively. The source parent node (e.g., the DU of the source parent node of network node 820) may forward the received handover command or RRC reconfiguration to the migration node (e.g., the MT of network node 820). In some examples, the source or target parent node of network node 820 may be a BS or an IAB host.

[0139] In operation 815, the network node 820 (eg, the MT of the network node 820) may perform a random access procedure with the target parent node (eg, the DU of the target parent node of the network node 820) and set up an RRC connection to the BS 810B (eg, the CU of the BS 810B).

[0140] In operation 817, BS 810A (e.g., the CU of BS 810A) may request a UE XnAP ID (e.g., the NG-RAN node UE XnAP ID) of the MT of network node 820 from BS 810B (e.g., the CU of BS 810B). As will be described later, the requested ID may be used on the Xn interface between BS 810B (e.g., the CU of BS 810B) and BS 810C (e.g., the CU of BS 810C).

[0141] For example, BS 810A (e.g., the CU of BS 810A) may transmit a request message to BS 810B (e.g., the CU of BS 810B) in operation 817. The request message may include an ID of BS 810C (e.g., the CU of BS 810C) and an ID associated with network node 820. In some examples, the ID of BS 810C may include the gNB ID of BS 810C or the gNB-CU ID of the CU of BS 810C. In some examples, the description regarding the ID associated with network node 720 may apply to the ID associated with network node 820. For example, the ID associated with network node 820 may be the UE XnAP ID of the MT of network node 820 assigned by BS 810B (e.g., ID#8B) or by BS 810A (e.g., ID#8A) and to be used on the Xn interface between BS 810A and BS 810B.

[0142] In some embodiments, the request message may include an indication explicitly requesting a UE XnAP ID. In some embodiments, such an indication may be implicitly derived from the ID of BS 810C (e.g., the CU of BS 810C). That is, when the request message includes the ID of BS 810C (e.g., the CU of BS 810C), BS 810B (e.g., the CU of BS 810B) may respond to BS 810A (e.g., the CU of BS 810A) with the UE XnAP ID of the MT of network node 820 (e.g., the NG-RAN node UE XnAP ID, represented as ID#8B') to be used on the Xn interface between BS 810B and BS 810C. In other words, in response to receiving the request message, BS 810B (e.g., the CU of BS 810B) may allocate ID#8B' and transmit a response message including ID#8B' to BS 810A (e.g., the CU of BS 810A).

[0143] In some embodiments, the request message may be (or be included in) a handover request message (e.g., as described with respect to operation 811). The response message may be (or be included in) a handover request confirmation message (e.g., as described with respect to operation 811). In some embodiments, the request message may be an XnAP message separate from the handover request message. The response message may be an XnAP message separate from the handover request confirmation message. In some embodiments, operation 817 may be performed at any stage in parallel with or after the handover preparation process (e.g., operation 811) and before operation 819.

[0144] In operation 819 , BS 810A (eg, the CU of BS 810A) may transmit a message to BS 810C (eg, the CU of BS 810C) to indicate that network node 820 (eg, the MT of network node 820) has switched to BS 810B (eg, the CU of BS 810B).

[0145] In some embodiments, the message in operation 819 may include an identifier of BS 810B (e.g., an ID of a CU of BS 810B) so that BS 810C (e.g., a CU of BS 810C) can trigger a TMM process to the correct non-F1 termination BS (e.g., a non-F1 termination CU, such as the CU of BS 810B). For example, the ID of BS 810B may be the gNB ID of BS 810B, the gNB-CU ID of the CU of BS 810B, the IP address of the CU of BS 810B, or any ID that can identify BS 810B (e.g., the CU of BS 810B).

[0146] In some embodiments, the message in operation 819 may include an ID associated with network node 820. As will be described later, the ID associated with network node 820 may be used to allow BS 810B (e.g., the CU of BS 810B) to identify network node 820. The ID associated with network node 820 may be a UE XnAP ID (e.g., ID#8B′) allocated by BS 810B (e.g., the CU of BS 810B) for the MT of network node 820 on the Xn interface between BS 810B and BS 810C.

[0147] Then, BS 810C (e.g., the CU of BS 810C) may trigger a TMM process (e.g., an IAB TMM process) to exchange information between BS 810C (e.g., the CU of BS 810C) and BS 810B (e.g., the CU of BS 810B) of network node 820 and manage the migration of network node 820 and descendant node traffic between topologies managed by the two BSs (e.g., the two CUs). For example, in operation 821, BS 810C (e.g., the CU of BS 810C) may transmit a TMM request message to BS 810B (e.g., the CU of BS 810B).

[0148] In some embodiments, the TMM request message may include an ID (e.g., ID#8B') associated with the network node 820, as described above with respect to operation 819. For example, in some embodiments, the TMM request message may include a non-F1-terminated BS UE XnAP ID IE (e.g., non-F1-terminated IAB-hosted UE XnAP ID IE). The IE may include an ID (e.g., ID#8B') associated with the network node 820. For example, the value of the IE may be the ID (e.g., ID#8B') associated with the network node 820, or the IE may be set to the ID (e.g., ID#8B') associated with the network node 820.

[0149] In some embodiments, the TMM request message may include an F1-terminating BS UE XnAPID IE (e.g., an F1-terminating IAB-host UE XnAP ID IE), which may include a UE XnAP ID (e.g., an NG-RAN node UE XnAPID) allocated by BS 810C (e.g., a CU of BS 810C) and to be used on the Xn interface between BS 810B and BS 810C. For example, the value of the F1-terminating BS UE XnAPID IE may be the UE XnAPID allocated by BS 810C, or the F1-terminating BS UE XnAPID IE may be set to the UE XnAPID allocated by BS 810C.

[0150] In some embodiments, in response to receiving the TMM request message, BS 810B (eg, the CU of BS 810B) may identify network node 820 based on the non-F1 terminating BS UE XnAP ID IE in the TMM request message because it contains an ID assigned by itself (eg, ID#8B').

[0151] After the above operations, BS 810B (e.g., the CU of BS 810B) and BS 810C (e.g., the CU of BS 810C) may have UE XnAP IDs allocated by each other for use on the Xn interface between BS 810B (e.g., the CU of BS 810B) and BS 810C (e.g., the CU of BS 810C).

[0152] In operation 823 , the BS 810B (eg, the CU of the BS 810B) may transmit a TMM response message to the BS 810C (eg, the CU of the BS 810C) as a response to the TMM request message.

[0153] In some embodiments, the TMM response message may include a non-F1-terminated BS UE XnAPID IE (e.g., a non-F1-terminated IAB-host UE XnAP ID IE), which is set to the same value as the non-F1-terminated BS UE XnAPID IE in the TMM request message. In some embodiments, the TMM response message may also include an F1-terminated BS UE XnAP ID IE (e.g., a F1-terminated IAB-host UE XnAP ID IE), which is set to the same value as the F1-terminated BS UE XnAPID IE in the TMM request message.

[0154] After the TMM process, BS 810B (eg, the CU of BS 810B) may update the BAP configuration, and F1 traffic between network node 820 and BS 810C (eg, the CU of BS 810C) may be transmitted via the BH link under BS 810B (eg, the CU of BS 810B).

[0155] Those skilled in the art will appreciate that the sequence of operations in exemplary process 800 may be changed, and some of the operations in exemplary process 800 may be eliminated or modified, without departing from the spirit and scope of the present disclosure.

[0156] For example, Figure 9 A flow chart illustrating an exemplary migration process 900 according to some embodiments of the present disclosure.

[0157] The details described in all the above embodiments of the present disclosure apply to Figure 9 . For example, BSs 910A to 910C may serve as IAB hosts as described above and may include a CU and at least one DU. Network node 920 may serve 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 migration, or two DUs during DU migration).

[0158] Network node 920 (e.g., a DU of network node 920) may have an F1 connection with BS 910A (e.g., a CU of BS 910A). Network node 920 (e.g., an MT of network node 920) may have an RRC connection with BS 910B (e.g., a CU of BS 910B). BS 910A and BS 910B may be referred to as an F1-terminated BS and a non-F1-terminated BS (or an RRC-terminated BS), respectively. The CU of BS 910A and the CU of BS 910B may be referred to as an F1-terminated BS-CU and a non-F1-terminated BS-CU (or an RRC-terminated BS-CU), respectively.

[0159] In some embodiments, the DU of network node 920 may perform migration from BS 910A (i.e., the source F1-terminating BS) to a target BS (i.e., the target F1-terminating BS, such as BS 910C), while the MT of network node 920 maintains its connection with BS 910B. For example, BS 910A, BS 910B, BS 910C, and network node 920 may function as Figure 5 The IAB host 510A, the IAB host 510B, the IAB host 510C and the IAB node 520D.

[0160] In some embodiments, BS 910A (e.g., the CU of BS 910A) may trigger migration of a DU of network node 920. For example, in operation 911 (indicated by a dashed arrow, as an option), BS 910A (e.g., the CU of BS 910A) may transmit an F1AP message to instruct network node 920 to trigger DU migration. For example, network node 920 may include a DU (denoted as DU#A1) having an F1 connection with BS 910A (e.g., the CU of BS 910A). BS 910A (e.g., the CU of BS 910A) may transmit the F1AP message to DU#A1.

[0161] In some embodiments, the F1AP message may include an ID of the BS 910C (e.g., a CU of the BS 910C). The ID of the BS 910C may be the gNB ID of the BS 910C, the gNB-CU ID of the CU of the BS 910C, the IP address of the CU of the BS 910C, or any ID that can identify the BS 910C (e.g., the CU of the BS 910C).

[0162] In some other embodiments, migration may be triggered by an operations administration and maintenance (OAM) entity or the network node 920 itself (eg, based on pre-configuration on the network node 920). In these embodiments, operation 911 may be omitted.

[0163] During the migration of a DU of network node 920, network node 920 may have an additional logical DU (denoted as DU#A2) in addition to DU#A1, wherein network node 920 (e.g., DU#A2) may need to set up an F1 connection to BS 910C (e.g., a CU of BS 910C). In response to the initiation or triggering of the DU migration, network node 920 (e.g., DU#A2) may transmit an F1 setup request message to BS 910C (e.g., a CU of BS 910C) in operation 921. For example, the F1 setup request message may first be transmitted to BS 910B (e.g., a DU of BS 910B) and then delivered to BS 910C (e.g., a CU of BS 910C) via IP routing.

[0164] In some embodiments, the F1 setup request message may include an ID of BS 910B (e.g., a CU of BS 910B) so that BS 910C (e.g., a CU of BS 910C) can trigger a TMM process to the correct non-F1-terminating BS (e.g., a non-F1-terminating CU, such as the CU of BS 910B). The ID of BS 910B may be the gNB ID of BS 910B, the gNB-CU ID of the CU of BS 910B, the IP address of the CU of BS 910B, or any ID that can identify BS 910B (e.g., the CU of BS 910B).

[0165] In some embodiments, the F1 setup request message may include an ID associated with the network node 920. As will be described later, the ID associated with the network node 920 may be used to allow the BS 910B (e.g., the CU of the BS 910B) to identify the network node 920. That is, any ID associated with the network node 920 known by the BS 910B (e.g., the CU of the BS 910B) may be employed.

[0166] For example, the ID associated with the network node 920 may be an ID of the MT of the network node 920, an ID of a DU (e.g., DU#A1) of the network node 920, or an ID of the network node 920. For example, the ID associated with the network node 920 may be a C-RNTI of the MT of the network node 920, a BS-DU ID (e.g., a gNB-DU ID) of a DU (e.g., DU#A1) of the network node 920, a BAP address of the network node 920, or a BS-DU UE F1AP ID (e.g., gNB-DU UE F1AP ID) of a DU (e.g., DU#A1) of the network node 920. For example, the ID associated with the network node 920 may be a UE XnAP ID of the MT of the network node 920 allocated by the BS 910A or BS 910B, which is to be used on the Xn interface between the BS 910A and the BS 910B. In this example, the network node 920 needs to obtain the UE XnAPID from the BS 910A or BS 910B in advance.

[0167] In response to receiving the F1 setup request message, BS 910C (e.g., the CU of BS 910C) may transmit an F1 setup response message to network node 920 (e.g., DU #A2) in operation 923. The F1 setup response message may include a list of cells that BS 910C (e.g., the CU of BS 910C) requests network node 920 (e.g., DU #A2) to activate. For example, the F1 setup response message may first be delivered to BS 910B (e.g., the DU of BS 910B) via IP routing and then transmitted to network node 920 via BAP routing.

[0168] Then, BS 910C (e.g., the CU of BS 910C) may trigger a TMM process (e.g., an IAB TMM process) to exchange information between BS 910C (e.g., the CU of BS 910C) and BS 910B (e.g., the CU of BS 910B) of network node 920 and manage the migration of network node 920 and descendant node traffic between topologies managed by the two BSs (e.g., the two CUs). For example, in operation 925, BS 910C (e.g., the CU of BS 910C) may transmit a TMM request message to BS 910B (e.g., the CU of BS 910B).

[0169] In some embodiments, the TMM request message may include an ID associated with network node 920 , as described above with respect to operation 921 .

[0170] In some embodiments, the TMM request message may include a non-F1 terminating BS UE XnAPID IE (eg, a non-F1 terminating IAB host-UE XnAP ID IE). Figure 6 As described, the F1-terminating BS (e.g., BS 910C) should include the UE XnAPID (e.g., NG-RAN node UE XnAPID) of the MT of the radio network node (e.g., network node 920) in the non-F1-terminating BS UE XnAP ID IE, which is allocated by the non-F1-terminating BS (e.g., BS 910B) and is to be used on the Xn interface between the F1-terminating BS (e.g., BS 910C) and the non-F1-terminating BS (e.g., BS 910B). For example, the value of the IE is an ID, or the IE is set to an ID. However, in Figure 9 In the example, the BS 910C (e.g., the CU of the BS 910C) does not have information of such UE XnAPID at operation 925. The BS 910C (e.g., the CU of the BS 910C) may set the non-F1 terminated BS UE XnAPID IE in the TMM request message to be invalid or disabled.

[0171] In some embodiments, the ID associated with the network node 920 may be included in an IE of the TMM request message that is different from the non-F1 terminating BS UE XnAPID IE.

[0172] In some embodiments, the TMM request message may include an F1-terminating BS UE XnAPID IE (e.g., an F1-terminating IAB-host UE XnAP ID IE), which may include a UE XnAP ID (e.g., an NG-RAN node UE XnAPID) allocated by BS 910C (e.g., a CU of BS 910C) and to be used on the Xn interface between BS 910C and BS 910B. For example, the value of the F1-terminating BS UE XnAP ID IE may be the UE XnAP ID allocated by BS 910C, or the F1-terminating BS UE XnAPID IE may be set to the UE XnAPID allocated by BS 910C.

[0173] In some embodiments, BS 910B (e.g., the CU of BS 910B) may identify network node 920 based on the ID associated with network node 920 in the TMM request message. In some embodiments, BS 910B (e.g., the CU of BS 910B) may ignore the non-F1-terminated BS UE XnAP ID IE in the TMM request message. For example, when the TMM request message includes the ID associated with network node 920, BS 910B (e.g., the CU of BS 910B) may ignore the non-F1-terminated BS UE XnAP ID IE.

[0174] In some embodiments, BS 910B (e.g., the CU of BS 910B) may allocate a UE XnAP ID (e.g., an NG-RAN node UE XnAP ID) of the MT of network node 920 for use on the Xn interface between BS 910B and BS 910C in response to receiving the TMM request message. For example, when the TMM request message includes an ID associated with network node 920, BS 910B (e.g., the CU of BS 910B) may allocate a UE XnAP ID to the MT of network node 920.

[0175] In operation 927, BS 910B (e.g., the CU of BS 910B) may transmit a TMM response message to BS 910C (e.g., the CU of BS 910C) as a response to the TMM request message. In some embodiments, the TMM response message may include a UE XnAP ID assigned by BS 910B (e.g., the CU of BS 910B) for use on the Xn interface between the F1-terminating BS (e.g., BS 910C) and the non-F1-terminating BS (e.g., BS 910B). For example, BS 910B (e.g., the CU of BS 910B) may set the non-F1-terminating BS UE XnAP ID IE (e.g., the non-F1-terminating IAB-Host UE XnAP ID IE) in the TMM response message to the assigned UE XnAP ID. For example, the value of the non-F1-terminating BS UE XnAP ID IE in the TMM response message is the assigned UE XnAP ID.

[0176] In some embodiments, the TMM response message may also include an F1-terminating BS UE XnAP ID IE (eg, F1-terminating IAB-host UE XnAPID IE), which is set to the same value as the F1-terminating BS UE XnAP ID IE in the TMM request message.

[0177] In some embodiments, BS 910C (e.g., the CU of BS 910C) may store the UE XnAPID assigned by BS 910B (e.g., the CU of BS 910B) in response to receiving the TMM response message. For example, when the TMM request message contains an invalid / invalid UE XnAPID (e.g., the non-F1-terminated BS UE XnAPID IE in the TMM request message is invalid or invalid), BS 910C (e.g., the CU of BS 910C) may store the UE XnAPID in the non-F1-terminated BS UE XnAPID IE in the corresponding TMM response message.

[0178] After the above operations, BS 910B (e.g., the CU of BS 910B) and BS 910C (e.g., the CU of BS 910C) may have UE XnAPID allocated by each other for use on the Xn interface between BS 910B (e.g., the CU of BS 910B) and BS 910C (e.g., the CU of BS 910C).

[0179] After the TMM process, BS 910B (e.g., the CU of BS 910B) may update the BAP configuration, and F1 traffic between network node 920 and BS 910C (e.g., the CU of BS 910C) may be transmitted via the BH link under BS 910B (e.g., the CU of BS 910B).

[0180] In some embodiments, after the F1 setup between DU#A2 and BS 910C (e.g., the CU of BS 910C), the network node 920 (e.g., DU#A1) may indicate the completion of the F1 setup for BS 910C (e.g., the CU of BS 910A) to BS 910A (e.g., the CU of BS 910A) in operation 931, and notify BS 910A (e.g., the CU of BS 910A) of the list of cells that BS 910C (e.g., the CU of BS 910C) requested the network node 920 (e.g., DU#A2) to activate.

[0181] In some embodiments, in response to receiving information in operation 931, BS 910A (e.g., the CU of BS 910A) may trigger in operation 933 a handover of a UE served by network node 920 (e.g., DU#A1) from BS 910A (e.g., the CU of BS 910A) to BS 910C (e.g., the CU of BS 910C).

[0182] Those skilled in the art will appreciate that the sequence of operations in exemplary process 900 may be changed, and some of the operations in exemplary process 900 may be eliminated or modified without departing from the spirit and scope of the present disclosure. For example, operations 931 and 933 may be performed in parallel with operations 925 and 927, or before operations 925 and 927.

[0183] For example, Figure 10 A flow chart illustrating an exemplary migration process 1000 according to some embodiments of the present disclosure.

[0184] The details described in all the above embodiments of the present disclosure apply to Figure 10 . For example, BSs 1010A to 1010C may serve as IAB hosts as described above and may include a CU and at least one DU. Network node 1020 may serve 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 migration, or two DUs during DU migration).

[0185] Network node 1020 (e.g., a DU of network node 1020) may have an F1 connection with BS 1010A (e.g., a CU of BS 1010A). Network node 1020 (e.g., an MT of network node 1020) may have an RRC connection with BS 1010B (e.g., a CU of BS 1010B). BS 1010A and BS 1010B may be referred to as an F1-terminated BS and a non-F1-terminated BS (or an RRC-terminated BS), respectively. The CU of BS 1010A and the CU of BS 1010B may be referred to as an F1-terminated BS-CU and a non-F1-terminated BS-CU (or an RRC-terminated BS-CU), respectively.

[0186] In some embodiments, the DU of network node 1020 may perform migration from BS 1010A (i.e., the source F1-terminating BS) to a target BS (i.e., the target F1-terminating BS, such as BS 1010C), while the MT of network node 1020 maintains its connection with BS 1010B. For example, BS 1010A, BS 1010B, BS 1010C, and network node 1020 may function as Figure 5 The IAB host 510A, the IAB host 510B, the IAB host 510C and the IAB node 520D.

[0187] In some embodiments, BS 1010A (e.g., the CU of BS 1010A) may trigger the migration of a DU of network node 1020. For example, in operation 1011 (indicated by a dashed arrow, as an option), BS 1010A (e.g., the CU of BS 1010A) may transmit an F1AP message to instruct network node 1020 to trigger DU migration. For example, network node 1020 may include a DU (denoted as DU#B1) having an F1 connection with BS 1010A (e.g., the CU of BS 1010A). BS 1010A (e.g., the CU of BS 1010A) may transmit the F1AP message to DU#B1.

[0188] In some embodiments, the F1AP message may include an ID of BS1010C (e.g., a CU of BS1010C). The ID of BS1010C may be a gNB ID of BS1010C, a gNB-CU ID of a CU of BS1010C, an IP address of the CU of BS1010C, or any ID that can identify BS1010C (e.g., a CU of BS1010C).

[0189] In some other embodiments, the migration may be triggered by an OAM entity or the network node 1020 itself (eg, based on pre-configuration on the network node 1020). In these embodiments, operation 1011 may be omitted.

[0190] In some embodiments, before the migration of the DU of the network node 1020, the network node 1020 may obtain the UE XnAP ID of its MT (e.g., NG-RAN node UE XnAP ID, represented as ID#10B'), which is allocated by the non-F1-terminated BS of the network node 1020 (e.g., BS1010B) and is to be used on the Xn interface between the target F1-terminated BS of the network node 1020 (e.g., BS1010C) and the non-F1-terminated BS (e.g., BS1010B).

[0191] For example, in operation 1013, the network node 1020 may transmit a request message for the UE XnAP ID (e.g., ID#10B′) of the MT of the network node 1020 to the BS 1010B (e.g., the CU of the BS 1010B). As will be described later, the requested ID may be used on the Xn interface between the BS 1010B (e.g., the CU of the BS 1010B) and the BS 1010C (e.g., the CU of the BS 1010C).

[0192] In some embodiments, the request message may include an ID of BS 1010C (e.g., a CU of BS 1010C). In some examples, the ID of BS 1010C may include the gNB ID of BS 1010C or the gNB-CU ID of the CU of BS 1010C.

[0193] In some embodiments, the request message may include an indication explicitly requesting a UE XnAP ID. In some embodiments, such an indication may be implicitly derived from the ID of BS1010C (e.g., the CU of BS1010C). That is, when the request message includes the ID of BS1010C (e.g., the CU of BS1010C), BS1010B (e.g., the CU of BS1010B) may respond to network node 1020 with the UE XnAP ID of the MT of network node 1020 (e.g., ID#10B') to be used on the Xn interface between BS1010B and BS1010C. In other words, in response to receiving the request message, BS1010B (e.g., the CU of BS1010B) may allocate ID#10B' and transmit a response message including ID#10B' to network node 1020 in operation 1015.

[0194] In some embodiments, the request message and the response message may be transmitted via RRC signaling.

[0195] During the migration of a DU of network node 1020, network node 1020 may have an additional logical DU (denoted as DU#B2) in addition to DU#B1, wherein network node 1020 (e.g., DU#B2) may need to set up an F1 connection to BS 1010C (e.g., a CU of BS 1010C). In operation 1021, network node 1020 (e.g., DU#B2) may transmit an F1 setup request message to BS 1010C (e.g., a CU of BS 1010C). For example, the F1 setup request message may first be transmitted to BS 1010B (e.g., a DU of BS 1010B) and then delivered to BS 1010C (e.g., a CU of BS 1010C) via IP routing.

[0196] In some embodiments, the F1 setup request message may include the ID of BS 1010B (e.g., a CU of BS 1010B) so that BS 1010C (e.g., a CU of BS 1010C) can trigger the TMM process to the correct non-F1 terminated BS (e.g., a non-F1 terminated CU, such as the CU of BS 1010B). The ID of BS 1010B may be the gNB ID of BS 1010B, the gNB-CU ID of the CU of BS 1010B, the IP address of the CU of BS 1010B, or any ID that can identify BS 1010B (e.g., the CU of BS 1010B).

[0197] In some embodiments, the F1 setup request message may include an ID associated with the network node 1020. As will be described later, the ID associated with the network node 1020 may be used by the BS 1010B (e.g., the CU of the BS 1010B) to identify the network node 1020. The ID associated with the network node 1020 may be the UE XnAPID (e.g., ID#10B') allocated by the BS 1010B (e.g., the CU of the BS 1010B) for the MT of the network node 1020 on the Xn interface between the BS 1010B and the BS 1010C.

[0198] In response to receiving the F1 setup request message, BS 1010C (e.g., the CU of BS 1010C) may transmit an F1 setup response message to network node 1020 (e.g., DU #B2) in operation 1023. The F1 setup response message may include a list of cells that BS 1010C (e.g., the CU of BS 1010C) requests network node 1020 (e.g., DU #B2) to activate. For example, the F1 setup response message may first be delivered to BS 1010B (e.g., the DU of BS 1010B) via IP routing and then transmitted to network node 1020 via BAP routing.

[0199] Then, BS1010C (e.g., the CU of BS1010C) may trigger a TMM process (e.g., an IAB TMM process) to exchange information between BS1010C (e.g., the CU of BS1010C) and BS1010B (e.g., the CU of BS1010B) of network node 1020 and manage the migration of network node 1020 and descendant node traffic between topologies managed by the two BSs (e.g., the two CUs). For example, in operation 1025, BS1010C (e.g., the CU of BS1010C) may transmit a TMM request message to BS1010B (e.g., the CU of BS1010B).

[0200] In some embodiments, the TMM request message may include an ID associated with the network node 1020 (e.g., ID#10B'), as described above with respect to operation 1021. For example, in some embodiments, the TMM request message may include a non-F1-terminating BS UE XnAP ID IE (e.g., a non-F1-terminating IAB-host UE XnAP ID IE). The IE may include an ID associated with the network node 1020 (e.g., ID#10B'). For example, the value of the IE may be the ID associated with the network node 1020 (e.g., ID#10B'), or the IE may be set to the ID associated with the network node 1020 (e.g., ID#10B').

[0201] In some embodiments, the TMM request message may include an F1-terminating BS UE XnAPID IE (e.g., an F1-terminating IAB-host UE XnAP ID IE), which may include a UE XnAPID (e.g., an NG-RAN node UE XnAPID) allocated by BS1010C (e.g., a CU of BS1010C) and to be used on the Xn interface between BS1010C and BS1010B. For example, the value of the F1-terminating BS UE XnAPID IE may be the UE XnAP ID allocated by BS1010C, or the F1-terminating BS UE XnAPID IE may be set to the UE XnAPID allocated by BS1010C.

[0202] In some embodiments, in response to receiving the TMM request message, BS 1010B (eg, the CU of BS 1010B) may identify network node 1020 based on the non-F1 terminating BS UE XnAPID IE in the TMM request message because it contains an ID assigned by itself (eg, ID#10B').

[0203] After the above operations, BS1010B (e.g., the CU of BS1010B) and BS1010C (e.g., the CU of BS1010C) may have UE XnAPID allocated by each other for use on the Xn interface between BS1010B (e.g., the CU of BS1010B) and BS1010C (e.g., the CU of BS1010C).

[0204] In operation 1027 , the BS 1010B (eg, the CU of the BS 1010B) may transmit a TMM response message to the BS 1010C (eg, the CU of the BS 1010C) as a response to the TMM request message.

[0205] In some embodiments, the TMM response message may include a non-F1-terminated BS UE XnAPID IE (e.g., a non-F1-terminated IAB-host UE XnAP ID IE), which is set to the same value as the non-F1-terminated BS UE XnAPID IE in the TMM request message. In some embodiments, the TMM response message may also include an F1-terminated BS UE XnAP ID IE (e.g., a F1-terminated IAB-host UE XnAP ID IE), which is set to the same value as the F1-terminated BS UE XnAPID IE in the TMM request message.

[0206] After the TMM process, BS1010B (eg, the CU of BS1010B) may update the BAP configuration, and F1 traffic between network node 1020 and BS1010C (eg, the CU of BS1010C) may be transmitted via the BH link under BS1010B (eg, the CU of BS1010B).

[0207] In some embodiments, after the F1 setup between DU#B2 and BS1010C (e.g., the CU of BS1010C), the network node 1020 (e.g., DU#B1) may indicate the completion of the F1 setup for BS1010C (e.g., the CU of BS1010C) to BS1010A (e.g., the CU of BS1010A) in operation 1031, and notify BS1010A (e.g., the CU of BS1010A) of the list of cells that BS1010C (e.g., the CU of BS1010C) requested the network node 1020 (e.g., DU#B2) to activate.

[0208] In some embodiments, in response to receiving the information in operation 1031, BS1010A (e.g., the CU of BS1010A) may trigger in operation 1033 a handover of a UE served by network node 1020 (e.g., DU#B1) from BS1010A (e.g., the CU of BS1010A) to BS1010C (e.g., the CU of BS1010C).

[0209] Those skilled in the art will appreciate that the sequence of operations in exemplary process 1000 may be changed, and some of the operations in exemplary process 1000 may be eliminated or modified without departing from the spirit and scope of the present disclosure. For example, operations 1031 and 1033 may be performed in parallel with operations 1025 and 1027, or performed before operations 1025 and 1027.

[0210] Figure 11 Flowchart illustrating an exemplary process 1100 for wireless communication according to some embodiments of the present disclosure. Figure 11 The exemplary process 1100 may be performed by a BS (eg, an IAB host).

[0211] refer to Figure 11 In operation 1111, the first BS may receive a TMM request message (eg, an IAB TMM request message) from the second BS, wherein the TMM request message may include an identifier associated with the wireless network node for the first BS to identify the wireless network node.

[0212] In operation 1113, the first BS may transmit a TMM response message (eg, an IAB TMM response message) to the second BS in response to receiving the TMM request message.

[0213] In some embodiments of the present disclosure, a mobile operator (MT) of the radio network node is handed over from a third BS to a first BS, and a DU of the radio network node has an F1 connection to the second BS. In some embodiments of the present disclosure, a DU of the radio network node is migrated from a fourth BS to a second BS, and a MT of the radio network node has an RRC connection to the first BS.

[0214] In some embodiments of the present disclosure, the first BS may be used as Figure 7 BS 710B, Figure 8 BS 810B, Figure 9 BS 910B or Figure 10 In some embodiments of the present disclosure, the second BS may be used as Figure 7 BS710C, Figure 8 BS 810C, Figure 9BS 910C or Figure 10 In some embodiments of the present disclosure, the wireless network node may be used as a BS1010C. Figure 7 The network node 720 in Figure 8 The network node 820 in Figure 9 Network node 920 or Figure 10 In some embodiments of the present disclosure, the third BS may be used as a network node 1020. Figure 7 BS 710A or Figure 8 In some embodiments of the present disclosure, the fourth BS may be used as Figure 9 BS 910A or Figure 10 BS1010A in.

[0215] In some embodiments of the present disclosure, the identifier associated with the radio network node may include one of the following: a C-RNTI of the MT of the radio network node, a BS-DUID of the DU of the radio network node (e.g., a gNB-DUID), a BAP address of the radio network node, a UE XnAP ID of the MT of the radio network node (e.g., an NG-RAN node UE XnAPID), and a BS-DU UE F1APID of the DU of the radio network node (e.g., a gNB-DU UE F1APID).

[0216] In some embodiments of the present disclosure, the UE XnAPID may be associated with the Xn interface between the first and third BSs. For example, the UE XnAP ID may be ID#7A or ID#7B as described above. In some embodiments of the present disclosure, the UE XnAPID may be associated with the first and second BSs. For example, the UE XnAPID may be ID#8B' or ID#10B' as described above.

[0217] In some embodiments of the present disclosure, during migration of a DU of the radio network node from a fourth BS to a second BS, the radio network node may include a first DU having an F1 connection to the fourth BS and a second DU having an F1 connection to the second BS. The BS-DUID of the DU of the radio network node is the BS-DUID of the first DU of the radio network node, and the BS-DU UE F1AP ID of the DU of the radio network node is the BS-DU UE F1AP ID of the first DU of the radio network node.

[0218] In some embodiments of the present disclosure, the TMM request message may include an IE indicating an identifier associated with the radio network node, and the IE is different from the non-F1 terminating BS UE XnAPID IE in the TMM request message. In some embodiments of the present disclosure, the first BS may ignore the non-F1 terminating BS UE XnAPID IE in the TMM request message.

[0219] In some embodiments of the present disclosure, in response to receiving a TMM request message, the first base station may allocate the UE XnAP ID of the mobile equipment (MT) of the radio network node for use on the Xn interface between the first base station and the second base station. The TMM response message may include the allocated UE XnAP ID. For example, the TMM response message may include a Non-F1 Terminating BS UE XnAP ID IE, and the value of the IE may be set to the allocated UE XnAP ID.

[0220] In some embodiments of the present disclosure, the identifier associated with the radio network node may include the UE XnAPID of the MT of the radio network node to be used on the Xn interface between the first BS and the second BS. In some embodiments of the present disclosure, the identifier associated with the radio network node is included in the non-F1 terminating BS UE XnAPID IE in the TMM request message. For example, the value of the IE is the identifier associated with the radio network node or the UE XnAPID. For example, the value of the IE is set to the identifier associated with the radio network node or the UE XnAPID of the MT of the radio network node to be used on the Xn interface between the first BS and the second BS.

[0221] In some embodiments of the present disclosure, a first BS may allocate a UE XnAP ID of a MT of a wireless network node for use on an Xn interface between the first BS and a second BS, and wherein the transceiver is further configured to transmit the allocated UE XnAP ID to a third BS or wireless network node. In some embodiments of the present disclosure, the first BS may receive a request message for the UE XnAP ID from the third BS or wireless network node, and wherein allocating the UE XnAP ID may include allocating the UE XnAP ID in response to receiving the request message. For example, Figure 8 The description of operation 817 in FIG. 1 is applicable here. For example, Figure 10 The description of operations 1013 and 1015 in FIG. 1 is applicable here.

[0222] For example, in some embodiments of the present disclosure, the request message is a handover request message from the third BS, and the allocated UE XnAP ID is transmitted in the handover request confirm message.

[0223] For example, in some embodiments of the present disclosure, the request message from the third BS may include an identifier of the second BS and an identifier associated with the radio network node.For example, in some embodiments of the present disclosure, the request message from the radio network node may include an identifier of the second BS.

[0224] Those skilled in the art will appreciate that the sequence of operations in exemplary process 1100 may be changed, and some of the operations in exemplary process 1100 may be eliminated or modified without departing from the spirit and scope of the present disclosure.

[0225] Figure 12 Flowchart illustrating an exemplary process 1200 for wireless communication according to some embodiments of the present disclosure. Figure 12 The exemplary process 1200 may be performed by a BS (eg, an IAB host).

[0226] refer to Figure 12 In operation 1211, the second BS may transmit a TMM request message (eg, an IAB TMM request message) to the first BS, wherein the TMM request message may include an identifier associated with the wireless network node for the first BS to identify the wireless network node.

[0227] In operation 1213, the second BS may receive a TMM response message (eg, an IAB TMM response message) from the first BS in response to transmitting the TMM request message.

[0228] In some embodiments of the present disclosure, a mobile operator (MT) of the radio network node is handed over from a third BS to a first BS, and a DU of the radio network node has an F1 connection to the second BS. In some embodiments of the present disclosure, a DU of the radio network node is migrated from a fourth BS to a second BS, and a MT of the radio network node has an RRC connection to the first BS.

[0229] In some embodiments of the present disclosure, the first BS may be used as Figure 7 BS 710B, Figure 8 BS 810B, Figure 9 BS 910B or Figure 10 In some embodiments of the present disclosure, the second BS may be used as Figure 7 BS710C, Figure 8 BS 810C, Figure 9 BS 910C or Figure 10 In some embodiments of the present disclosure, the wireless network node may be used as a BS1010C. Figure 7 The network node 720 in Figure 8The network node 820 in Figure 9 Network node 920 or Figure 10 In some embodiments of the present disclosure, the third BS may be used as a network node 1020. Figure 7 BS 710A or Figure 8 In some embodiments of the present disclosure, the fourth BS may be used as Figure 9 BS 910A or Figure 10 BS1010A in.

[0230] In some embodiments of the present disclosure, the second BS may receive an identifier associated with the radio network node from the third BS. In some embodiments of the present disclosure, the identifier associated with the radio network node may include one of the following: a C-RNTI of a mobile station of the radio network node, a BS-DUID of a DU of the radio network node (e.g., a gNB-DUID), a BAP address of the radio network node, and a UE XnAP ID of a mobile station of the radio network node (e.g., an NG-RAN node UE XnAP ID).

[0231] In some embodiments of the present disclosure, the UE XnAPID may be associated with the Xn interface between the first and third BSs. For example, the UE XnAP ID may be ID#7A or ID#7B as described above. In some embodiments of the present disclosure, the UE XnAPID may be associated with the first and second BSs. For example, the UE XnAPID may be ID#8B' as described above.

[0232] In some embodiments of the present disclosure, the second BS may receive an identifier associated with the radio network node from the radio network node. In some embodiments of the present disclosure, the identifier associated with the radio network node may include one of the following: a C-RNTI of a mobile station of the radio network node, a BS-DU ID of a DU of the radio network node (e.g., a gNB-DU ID), a BAP address of the radio network node, a UE XnAP ID of a mobile station of the radio network node (e.g., an NG-RAN node UE XnAP ID), and a BS-DU UE F1AP ID of a DU of the radio network node (e.g., a gNB-DU UE F1AP ID). In some embodiments of the present disclosure, the UE XnAP ID may be associated with the first and second BSs. For example, the UE XnAP ID may be ID#10B' as described above.

[0233] In some embodiments of the present disclosure, during migration of a DU of the radio network node from a fourth BS to a second BS, the radio network node may include a first DU having an F1 connection to the fourth BS and a second DU having an F1 connection to the second BS. The BS-DUID of the DU of the radio network node is the BS-DUID of the first DU of the radio network node, and the BS-DU UE F1AP ID of the DU of the radio network node is the BS-DU UE F1AP ID of the first DU of the radio network node.

[0234] In some embodiments of the present disclosure, the TMM request message may include an IE indicating an identifier associated with the radio network node, and the IE is different from the non-F1-terminating BS UE XnAPID IE in the TMM request message. In some embodiments of the present disclosure, the second BS may set the non-F1-terminating BS UE XnAPID IE in the TMM request message to be invalid or disabled.

[0235] In some embodiments of the present disclosure, the TMM response message may include a UE XnAPID allocated by the first BS to the MT of the radio network node for use on the Xn interface between the first BS and the second BS. For example, the TMM response message may include a Non-F1 Terminated BS UE XnAP ID IE, and the value of the IE may be set to the UE XnAPID allocated by the first BS. In some embodiments of the present disclosure, the second BS may store the UE XnAPID allocated by the first BS.

[0236] In some embodiments of the present disclosure, the identifier associated with the radio network node may include a UE XnAPID assigned by a first BS to a MT of the radio network node for use on an Xn interface between the first BS and a second BS. In some embodiments of the present disclosure, the identifier associated with the radio network node is included in a non-F1 terminating BS UE XnAPID IE in a TMM request message. For example, the value of the IE is an identifier associated with the radio network node or a UE XnAP ID assigned by the first BS. For example, the value of the IE is set to an identifier associated with the radio network node or a UE XnAPID assigned by the first BS.

[0237] In some embodiments of the present disclosure, an identifier associated with a radio network node is received in an F1 Setup Request message.

[0238] Those skilled in the art will appreciate that the sequence of operations in exemplary process 1200 may be changed, and some of the operations in exemplary process 1200 may be eliminated or modified, without departing from the spirit and scope of the present disclosure.

[0239] Figure 13A block diagram illustrating an exemplary device 1300 according to some embodiments of the present disclosure.

[0240] like Figure 13 , apparatus 1300 may include at least one processor 1306 and at least one transceiver 1302 coupled to the processor 1306. Apparatus 1300 may be a (wireless) network node (e.g., an IAB node), a base station (e.g., an IAB host, an IAB host-CU, or an IAB host-DU), a DU of a base station, or a CU of a base station. If apparatus 1300 is a base station, apparatus 1300 may further include a CU and at least one DU coupled to the CU. The CU and the DU may be co-located or separately located. The CU and the DU may be coupled to processor 1306. If apparatus 1300 is a (wireless) network node (fixed or mobile), apparatus 1300 may further include a mobile station (MT) and a DU coupled to the MT. The MT and the DU may be coupled to processor 1306.

[0241] Although elements such as at least one transceiver 1302 and a processor 1306 are described in the singular in this figure, the plural form is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 1302 may be divided into two devices, such as a receive circuit system and a transmit circuit system. In some embodiments of the present application, the apparatus 1300 may further include an input device, a memory, and / or other components.

[0242] In some embodiments of the present application, the device 1300 may be a BS. The processor 1306 may interact with other elements of the device 1300 (eg, the transceiver 1302, the DU, or the CU) to perform Figures 1 to 12 In some embodiments of the present application, the device 1300 may be a (wireless) network node. The transceiver 1302 and the processor 1306 may interact with each other to perform Figures 1 to 12 The operations described in

[0014] relate to network nodes or IAB nodes (mobile or fixed).

[0243] In some embodiments of the present application, the apparatus 1300 may further include at least one non-transitory computer-readable medium.

[0244] In some embodiments of the present disclosure, a non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1306 to implement the method described above with respect to the BS, IAB host, IAB host-CU, or IAB host-DU. For example, when the computer-executable instructions are executed, the processor 1306 interacts with, for example, the transceiver 1302 to perform Figures 1 to 12The operations described in BS, IAB Host, IAB Host-CU or IAB Host-DU.

[0245] For example, in some embodiments of the present disclosure, a non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1306 to implement the method described above with respect to a network node or an IAB node (mobile or fixed). For example, when the computer-executable instructions are executed, the processor 1306 interacts with the transceiver 1302 to perform Figures 1 to 12 The operations described in

[0014] relate to network nodes or IAB nodes (mobile or fixed).

[0246] Those skilled in the art will appreciate that the operations or steps of the methods described in conjunction with the aspects disclosed herein may be implemented directly in hardware, in a software module executed by a processor, or in a combination of the two. The 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. Furthermore, in some aspects, the operations or steps of the methods may reside as one or any combination or set of codes and / or instructions on a non-transitory computer-readable medium that can be incorporated into a computer program product.

[0247] Although 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, the various components of an embodiment may be interchanged, added, or replaced in other embodiments. In addition, not all elements of each figure are necessary for the operation of the disclosed embodiments. For example, it will enable a person of ordinary skill in the art of the disclosed embodiments to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure as set forth herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0248] In this document, the terms "switch", "path switching" and "migration" are used interchangeably. The term "includes, including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements not only include those elements, but also may include other elements that are not explicitly listed or inherent to such processes, methods, articles or equipment. In the absence of more constraints, an element starting with "a, an" or the like does not exclude the presence of additional identical elements in the process, method, article or equipment comprising the element. In addition, the term "another" is defined as at least a second or more. As used herein, the term "having" and the like are defined as "including". For example, the expression of "A and / or B" or "at least one of A and B" may include any and all combinations of the words listed together with the expression. For example, the expression "A and / or B" or "at least one of A and B" may include A, B or both A and B. The wording "first", "second" or the like is only used to clearly illustrate the embodiments of the present application, and is not used to limit the substantive content of the present application.

Claims

1. A first base station BS, comprising: processor; and a transceiver coupled to the processor, wherein the transceiver is configured to: receiving a transport migration management (TMM) request message from a second BS, wherein the TMM request message includes an identifier associated with a radio network node for the first BS to identify the radio network node; and transmitting a TMM response message to the second BS in response to receiving the TMM request message, wherein a mobile terminal MT of the radio network node is handed over from a third BS to the first BS, and a distributed unit DU of the radio network node has an F1 connection to the second BS, or wherein the DU of the radio network node is migrated from a fourth BS to the second BS, and the MT of the radio network node has a radio resource control RRC connection to the first BS.

2. The first BS according to claim 1, wherein the identifier associated with the radio network node comprises one of the following: a cell radio network temporary identifier (C-RNTI) of the MT of the radio network node, a BS-DU identifier (ID) of the DU of the radio network node, a backhaul adaptation protocol (BAP) address of the radio network node, a user equipment (UE) Xn application protocol (XnAPID) of the MT of the radio network node, and a BS-DU UE F1 application protocol (F1APID) of the DU of the radio network node.

3. The first BS according to claim 1 or 2, wherein the TMM request message includes an information element (IE) indicating the identifier associated with the radio network node, and the IE is different from a non-F1 terminating BS UE XnAPID IE in the TMM request message; and Wherein the processor is configured to ignore the non-F1 terminated BS UEXnAPID IE in the TMM request message.

4. The first BS according to claim 1 or 2, wherein the identifier associated with the radio network node comprises a UE XnAP ID of the MT of the radio network node to be used on an Xn interface between the first BS and the second BS.

5. The first BS of claim 4 , wherein the processor is configured to allocate the UE XnAPID of the MT of the wireless network node for use on the Xn interface between the first BS and the second BS, and wherein the transceiver is further configured to transmit the allocated UE XnAPID to the third BS or the wireless network node.

6. The first BS of claim 5, wherein the transceiver is further configured to receive a request message for the UE XnAP ID from the third BS or the wireless network node, and wherein allocating the UE XnAP ID comprises allocating the UE XnAP ID in response to receiving the request message.

7. The first BS of claim 6, wherein the request message from the third BS includes an identifier of the second BS and the identifier associated with the wireless network node; or wherein the request message from the wireless network node includes the identifier of the second BS.

8. A second base station BS, comprising: processor; and a transceiver coupled to the processor, wherein the transceiver is configured to: transmitting a transport migration management (TMM) request message to the first BS, wherein the TMM request message includes an identifier associated with the radio network node for the first BS to identify the radio network node; and receiving a TMM response message from the first BS in response to transmitting the TMM request message, wherein a mobile terminal MT of the radio network node is handed over from a third BS to the first BS, and a distributed unit DU of the radio network node has an F1 connection to the second BS, or wherein the DU of the radio network node is migrated from a fourth BS to the second BS, and the MT of the radio network node has a radio resource control RRC connection to the first BS.

9. The second BS of claim 8, wherein the transceiver is further configured to receive the identifier associated with the wireless network node from the third BS, and The identifier associated with the radio network node includes one of the following: a cell radio network temporary identifier C-RNTI of the MT of the radio network node, a BS-DU identifier ID of the DU of the radio network node, a backhaul adaptation protocol BAP address of the radio network node, and a user equipment UE Xn application protocol XnAPID of the MT of the radio network node.

10. The second BS of claim 8, wherein the transceiver is further configured to receive the identifier associated with the wireless network node from the wireless network node, and The identifier associated with the radio network node includes one of the following: a cell radio network temporary identifier C-RNTI of the MT of the radio network node, a BS-DU identifier ID of the DU of the radio network node, a backhaul adaptation protocol BAP address of the radio network node, a user equipment UE Xn application protocol XnAP ID of the MT of the radio network node, and a BS-DU UE F1 application protocol F1APID of the DU of the radio network node.

11. The second BS according to any one of claims 8 to 10, wherein the TMM request message includes an information element (IE) indicating the identifier associated with the radio network node, and the IE is different from a non-F1 terminating BS UE XnAPID IE in the TMM request message. 12 . The second BS according to claim 11 , wherein the processor is configured to set the non-F1 terminating BS UE XnAPID IE in the TMM request message to be invalid or disabled.

13. The second BS of claim 11, wherein the TMM response message includes a UE XnAPID allocated by the first BS to the MT of the radio network node for use on an Xn interface between the first BS and the second BS.

14. The second BS according to any one of claims 8 to 10, wherein the identifier associated with the radio network node comprises a UE XnAPID allocated by the first BS to the MT of the radio network node for use on an Xn interface between the first BS and the second BS.

15. A method performed by a first base station BS, comprising: receiving a transport migration management (TMM) request message from a second BS, wherein the TMM request message includes an identifier associated with a radio network node for the first BS to identify the radio network node; and transmitting a TMM response message to the second BS in response to receiving the TMM request message, wherein a mobile terminal MT of the radio network node is handed over from a third BS to the first BS, and a distributed unit DU of the radio network node has an F1 connection to the second BS, or wherein the DU of the radio network node is migrated from a fourth BS to the second BS, and the MT of the radio network node has a radio resource control RRC connection to the first BS.

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