CN118202705A - Method and apparatus for mobility handling for mobile IAB deployments - Google Patents

Abstract

Methods and apparatus for wireless communication are disclosed. A method includes receiving at a base station at least one handover tag of a first Integrated Access and Backhaul (IAB) node, the at least one handover tag including a third group identity indicating a third group of terminal devices to be served by the first IAB node or including a fourth group identity indicating a fourth group of terminal devices not to be served by the first IAB node; receiving at least one handover tag comprising a first group identity indicating a first group of terminal devices to be served by a second IAB node or comprising a second group identity indicating a second group of terminal devices not to be served by the second IAB node; matching at least one handover tag of the IAB node with at least one handover tag for the terminal device; and based at least in part on the matching, initiate a procedure related to a handover of the terminal device to or from the first IAB node.

Description

Method and apparatus for mobility handling for mobile IAB deployments

Technical Field

Embodiments of the present disclosure relate generally to wireless communications and, more particularly, relate to methods and apparatus for mobility handling for mobile Integrated Access and Backhaul (IAB) deployments.

Background

The need for improved 5G cellular coverage and connectivity continues to increase, which can be challenging in many outdoor and mobility scenarios. In New Radio (NR), integrated Access and Backhaul (IAB) technologies are proposed to support flexible extensions of the Radio Access Network (RAN). The IAB supports wireless relay in a radio access network. A relay node, called an IAB node, supports access and backhaul via NR. The RAN is wirelessly connected by an IAB node to an NR base station (gNB) capable of serving IAB-nodes (referred to as an IAB-donor (IAB donor), which represents a general gNB with additional functionality to support IABs) to support IABs.

A large number of IAB-nodes may be deployed to provide acceptable coverage to multiple User Equipments (UEs) (hereinafter also referred to as IAB cells or cells of IABs). The UE may be served by an IAB cell, or by a cell from an IAB-donor (IAB donor), or by a cell from a conventional gNB.

There is a need for enhancements to mobility handling for UEs in IAB deployments, especially mobile IAB deployments. For mobile IAB-nodes installed on vehicles (e.g. buses, trains, planes), the IAB cell will be considered as an interior cell for mainly serving UEs inside the vehicle. For UEs outside the vehicle, the UE will be served by other cells (also referred to as outside cells). Then, when UEs enter the vehicle or leave the vehicle, they will be handed over between the IAB cell (or inner cell) and other cells (or outer cells). Since there may be a large number of UEs entering or exiting the vehicle, it would be desirable to efficiently and accurately switch these UEs between the IAB cell and other cells.

Disclosure of Invention

This summary is provided to introduce simplified concepts for mobility handling for mobile IAB deployments. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

According to a first aspect of the present disclosure, an apparatus is provided. The apparatus may include at least one processor and a memory including at least one of computer program code, the at least one memory and the at least one computer program code configured to, with the at least one processor, operate to cause the apparatus to: obtaining at least one handover tag for a terminal device, the at least one handover tag comprising a first group identity indicating a first group of terminal devices to be served by an IAB node or comprising a second group identity indicating a second group of terminal devices not to be served by the IAB node; and transmitting at least one handover tag to the at least one base station such that a procedure related to a handover of the terminal device to or from the IAB node can be initiated by the at least one base station based at least in part on the at least one handover tag. The at least one base station may comprise a normal base station and/or an IAB donor.

In one embodiment, the at least one handover tag may comprise a first handover tag for the terminal device, the first handover tag indicating a first group of terminal devices to be served by the IAB node. The at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: the method includes transmitting a first handoff tag to a first base station of the at least one base station such that a procedure related to a handoff of the terminal device to the IAB node can be initiated based at least in part on the first handoff tag.

In one embodiment, the at least one handover tag may comprise a second handover tag for the terminal device, the second handover tag indicating a second group of terminal devices that are not to be served by the IAB node. The at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: a second handover tag is transmitted to a second base station of the at least one base station such that a procedure related to a handover of the terminal device from the IAB node is initiated based at least in part on the second handover tag.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: a request for at least one handoff tag is received from at least one base station. The at least one handoff tag may be transmitted in response to a request for the at least one handoff tag.

In another embodiment, transmitting the at least one handoff tag may be transmitted without a request from the at least one base station.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to transmit the second handoff tag by at least one of: when the terminal equipment is switched to the second base station, sending a second switching label to the first base station so as to forward the second switching label to the second base station; after detecting that the terminal equipment is located near the second base station, sending a second switching label to the second base station; and after the terminal equipment detects the cell served by the second base station, sending a second handover label to the second base station.

In one embodiment, the apparatus may be included in the terminal device.

In another embodiment, the apparatus may be included in a core network node. In one example, the core network node may include access and mobility functions. The first and/or second handoff labels may be transmitted in the context of the terminal device. In another example, the core network node may include a location management function, and the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: a set of handover labels including a plurality of handover labels for a plurality of terminal devices is transmitted to at least one base station. The set of handover labels comprises at least one handover label for the terminal device.

In one embodiment, the at least one switch tag may further include: a first type indicator indicating whether a first group of terminal devices indicated by a first group identification of a handover label are to be served by an IAB node; or a second type indicator indicating whether a second group of terminal devices indicated by a second group identity will be served by the IAB node.

In one embodiment, the at least one switch tag may further include: identification of the cell; and/or an expiration time of at least one handoff tag.

According to a second aspect of the present disclosure, an apparatus at a base station is provided. The apparatus may include at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, operate to cause the apparatus to: receiving at least one handover tag of the first IAB node, the at least one handover tag comprising a third group identity indicating a third group of terminal devices to be served by the first IAB node or comprising a fourth group identity indicating a fourth group of terminal devices not to be served by the first IAB node; receiving at least one handover tag for a terminal device, the at least one handover tag comprising a first group identity indicating a first group of terminal devices to be handed over to be served by a second IAB node, or comprising a second group identity indicating a second group of terminal devices not to be served by the second IAB node; matching at least one handover tag of the first IAB node with at least one handover tag for the terminal device; and initiate a procedure related to a handover of the terminal device to or from the first IAB node based at least in part on a match of the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device.

In one embodiment, the at least one handover tag of the first IAB node may be received from the first IAB node or from another base station.

In one embodiment, the at least one handover tag for the terminal device may be received from the terminal device or the core network node. In another embodiment, at least one handover tag for the terminal device may be received from a further source base station.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: a request for at least one handover tag for a terminal device is sent to the terminal device or core network node. The received at least one handover tag for the terminal device may be transmitted in response to the request.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to match at least one handover tag of the first IAB node with at least one handover tag for the terminal device by at least one of: determining whether the first group identification is included in or the same as the third group identification; and determining whether the second group identification is included in or the same as the fourth group identification.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to match the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device by at least one of: determining that the handover of the terminal device is to be a handover to the first IAB node when the at least one handover tag of the terminal device indicates that the third group of terminal devices is to be served by the first IAB node and the at least one handover tag for the terminal device indicates that the first group of terminal devices is to be served by the second IAB node; and determining that the terminal device is handed over from the first IAB node when the at least one handover tag of the first IAB node indicates that the fourth group of terminal devices will not be served by the first IAB node and the at least one handover tag for the terminal device indicates that the second group of terminal devices will not be served by the second IAB node.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to match the first switch tag with the second switch tag by: determining a target cell for handover based on at least one handover tag of the first IAB node and/or at least one handover tag for the terminal device; and determining that the terminal device is an applicable terminal device for handover based on at least one handover tag of the first IAB node and/or at least one handover tag for the terminal device.

In one embodiment, the at least one switch tag may further include: a third type indicator indicating whether a third group of terminal devices indicated by a third group identity are to be served by the first IAB node; or a fourth type indicator indicating whether the fourth group of terminal devices indicated by the fourth group identity will not be served by the first IAB node. The at least one handover tag for the terminal device may further include: a first type indicator indicating whether a first group of terminal devices indicated by a first group identity are to be served by a second IAB node; or a second type indicator indicating whether the second group of terminal devices indicated by the second group identity will not be served by the second IAB node.

In one embodiment, the procedure may include a preparation procedure for handover of the terminal device.

According to a third aspect of the present disclosure, an apparatus at an IAB node is provided. The apparatus may include at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, operate to cause the apparatus to: obtaining at least one handover tag for the IAB node, the at least one handover tag comprising a third group identity indicating a third group of terminal devices to be served by the IAB node or comprising a fourth group identity indicating a fourth group of terminal devices not to be served by the IAB node; and transmitting at least one handover tag to the IAB donor such that a procedure can be initiated by the IAB donor based at least in part on the at least one handover tag, wherein the procedure is related to a handover of a terminal device of the third or fourth group of terminal devices to or from the IAB node.

In one embodiment, the at least one handover tag may comprise a third handover tag indicating a third group of terminal devices to be served by the IAB node. The third handoff tag is sent to the IAB donor such that the process can be initiated based at least in part on the third handoff tag.

In one embodiment, the at least one handover tag may comprise a fourth handover tag indicating that the fourth group of terminal devices will not be served by the IAB node. The fourth handoff tag is sent to the IAB donor such that the process can be initiated based at least in part on the fourth handoff tag.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: a request is sent to the terminal device for reporting to the IAB donor at least one handover tag for the terminal device. The at least one handover tag for the terminal device may indicate a first group of terminal devices to be served by the IAB node, or a second group of terminal devices not to be served by the IAB node.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to: receiving at least one handover tag for a terminal device from the terminal device, wherein the at least one handover tag for the terminal device indicates a first group of terminal devices to be served by the IAB node or a second group of terminal devices not to be served by the IAB node; and forwarding at least one handover label for the terminal device to the IAB donor.

In one embodiment, the at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus to send at least one handoff tag of an IAB node to an IAB donor by: when an IAB node is connected to an IAB donor, at least one handover tag of the IAB node is sent to the IAB donor.

According to a first aspect of the present disclosure, a method is provided. The method comprises obtaining at least one handover tag for a terminal device, the at least one handover tag comprising a first group identity indicating a first group of terminal devices to be served by the IAB node, or comprising a second group identity indicating a second group of terminal devices not to be served by the IAB node. The method also includes transmitting at least one handoff tag to the at least one base station such that a procedure related to a handoff of the terminal device to or from the IAB node can be initiated by the at least one base station based at least in part on the at least one handoff tag. The base station may be a normal base station and/or an IAB donor.

According to a fifth aspect of the present disclosure, a method performed at a base station is provided. The method comprises the following steps: receiving at least one handover tag of the first IAB node, the at least one handover tag comprising a third group identity indicating a third group of terminal devices to be served by the first IAB node or comprising a fourth group identity indicating a fourth group of terminal devices not to be served by the first IAB node; receiving at least one handover tag for a terminal device, the at least one handover tag comprising a first group identity indicating a first group of terminal devices to be served by a second IAB node or comprising a second group identity indicating a second group of terminal devices not to be served by the second IAB node; matching at least one handover tag of the first IAB node with at least one handover tag for the terminal device; and initiate a procedure related to a handover of the terminal device to or from the first IAB node based at least in part on a match of the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device. The base station may be a normal base station or an IAB donor.

According to a sixth aspect of the present disclosure, there is provided a method performed at an IAB node. The method comprises the following steps: obtaining at least one handover tag for the IAB node, the at least one handover tag comprising a third group identity indicating a third group of terminal devices to be served by the IAB node or comprising a fourth group identity indicating a fourth group of terminal devices not to be served by the IAB node; and transmitting at least one handover tag to the IAB donor such that a procedure can be initiated based at least in part on the handover tag, wherein the procedure is related to a handover of a terminal device of the third or fourth group of terminal devices to or from the IAB node.

According to a seventh aspect of the present disclosure, there is provided a computer readable storage medium having instructions stored thereon, which when executed by at least one processor, cause the at least one processor to perform any of the methods according to the fourth, fifth and/or sixth aspects.

According to an eighth aspect of the present disclosure, there is provided a computer program product comprising instructions which, when executed by at least one processor, cause the at least one processor to perform any of the methods according to the first, second and/or third aspects.

These and other objects, features and advantages of the present disclosure will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

Drawings

Some example embodiments will now be described with reference to the accompanying drawings, in which:

fig. 1 illustrates an example of an IAB network architecture in which embodiments of the present disclosure may be implemented;

FIG. 2 illustrates an exemplary scenario for mobile IAB deployment;

Fig. 3 shows an exemplary procedure for mobility processing for mobile IAB deployments according to embodiments of the disclosure;

fig. 4 shows another exemplary procedure for mobility processing for mobile IAB deployments according to embodiments of the disclosure;

Fig. 5 shows yet another exemplary procedure for mobility processing for mobile IAB deployments according to embodiments of the disclosure;

FIG. 6 is a flow chart depicting a method according to an embodiment of the present disclosure;

FIG. 7 is a flow chart depicting a method according to an embodiment of the present disclosure;

FIG. 8 is a flow chart depicting a method according to an embodiment of the present disclosure; and

Fig. 9 shows a simplified block diagram of an apparatus according to an embodiment of the present disclosure.

Detailed Description

Some example embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments are shown. Indeed, example embodiments may take many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

According to some example embodiments, the terms "data," "content," "information," and similar terms may be used interchangeably to refer to data capable of being transmitted, received, operated on, and/or stored. In addition, the term "exemplary" as may be used herein is not provided to convey any qualitative assessment, but instead merely to convey an illustration of an example. Thus, use of any such terms should not be taken to limit the spirit and scope of embodiments of the present invention.

The present disclosure is directed to mobility handling for mobile IAB deployments. In New Radios (NRs), IAB techniques rely on partitioning a gNB architecture that includes a Central Unit (CU) and Distributed Units (DUs). Fig. 1 illustrates an example of an IAB network architecture 100 in which embodiments of the present disclosure may be implemented.

Architecture 100 includes an IAB-node (shown as 110 in fig. 1), one or more IAB nodes (shown as 120, 130 in fig. 1), and one or more terminal devices (e.g., shown as UEs 151, 152, 153 in fig. 1). IAB-donor 110 is a base station that provides network access to a UE (e.g., shown as UE 153 in fig. 1). The IAB-donor 110 also provides network access to an IAB node (e.g., shown as IAB 120 in fig. 1) via a network of backhaul and access links. The IAB-donor 110 is connected to a core network, such as a Next Generation Core (NGC) network 140. The IAB-nodes 120, 130 are access nodes that support NR access links to UEs and connect to parent and child nodes using NR backhaul links. In this architecture 100, IAB-donor 110 includes a CU (also referred to as an IAB-donor-CU, as shown at 112) and one or more DUs (also referred to as IAB-donor-DUs, as shown at 111). The IAB-donor-CU 112 is a logical node hosting the RRC (radio resource control) of the gNB, the Service Data Adaptation Protocol (SDAP) and Packet Data Convergence Protocol (PDCP) protocols, or the RRC and PDCP protocols of the en-gNB, controlling the operation of one or more IAB-donor-DUs. The IAB-donor-CU 112 terminates the F1 interface to the IAB-node and IAB-donor-DU.

The parent node is the next-hop neighbor node of the IAB-MT. The parent node may be an IAB-node or an IAB-donor-DU. The child node is the next hop neighbor node of the IAB-node or IAB-donor-DU. The child node is also an IAB-node. The IAB-node is connected to the IAB-donor-DU via one or more hops. The direction toward the child node is referred to as downstream, while the direction toward the parent node is referred to as upstream. The IAB-donor-CU performs centralized resource, topology and route management on the IAB topology.

IAB-donor-DU 111 is a logical node that hosts the Radio Link Control (RLC), medium Access Control (MAC), and Physical (PHY) layers of the gNB or en-gNB. The IAB-donor-DU 111 also hosts an IAB Backhaul Adaptation Protocol (BAP) sublayer that provides wireless backhaul to the IAB-node. The operation of the IAB-donor-DU is controlled in part by the IAB-donor-CU. One IAB-donor-DU supports one or more cells. One cell is supported by only one IAB-donor-DU. The IAB-donor-DU terminates the F1 interface connected to the IAB-donor-CU. The IAB-donor-DU provides wireless backhaul to downstream IAB-nodes and UEs via network functions of the NR Uu interface.

Each IAB-node has a DU function and a Mobile Terminal (MT) function. For example, as shown in FIG. 1, IAB-node 120 includes DU 121 (also referred to as IAB-DU) and MT 122 (also referred to as IAB-MT). IAB-node 130 includes DU 131 and MT 132. The function of the IAB-DU is similar to that of the IAB-donor-DU. The IAB-DU is a DU function supported by the IAB-node to terminate the NR access interface to the UE and the next hop IAB-node (i.e., child node), and the F1 protocol to terminate the IAB-donor-CU function on the IAB-donor. An IAB-node may comprise one or more DUs and one or more MTs. Each DU part of an IAB-node has an F1-C connection with only one control plane of one IAB-donor-CU. One IAB-DU supports one or more cells. One cell is supported by only one IAB-DU. From the UE's point of view, these cells will be considered as normal cells. In other words, for the UE, there is no distinction between the cell provided by the IAB-DU and the cell provided by the normal gNB.

To communicate with a parent node (which may be another IAB node or IAB-node), the IAB-node hosts Mobile Terminal (MT) functions corresponding to, or part of, UE operation. The IAB-MT is an IAB-node function that terminates the Uu interface to the parent node using procedures and actions specified for the UE, unless otherwise specified. The IAB-node is connected to an upstream IAB-node or IAB-donor-DU via a subset of the UE functions of the NR Uu interface, i.e. the IAB-MT functions of the IAB-node. The IAB-MT supports a subset of UE functions including, for example, physical layer, layer 2, RRC, and non-access stratum (NAS) functions to connect to DUs of another IAB-node or IAB-donor to connect to CUs on the IAB-donor and the core network.

In this architecture 100, IAB-node 120 is the parent node of IAB-node 130. IAB-node 110 is the parent node of IAB-nodes 120 and 130. Connected to upstream IAB-node 120 via IAB-MT 132, IAB-node 130. Via the IAB-DU 131, the IAB-node130 establishes RLC-channels to the UE 151 and to MTs of its downstream IAB-nodes (not shown). Via an IAB-MT 122, an IAB-node 120 is connected to an IAB-donor 110. Via the IAB-DU 121, the IAB-node 120 establishes RLC-channels to the UE 152 and to MTs of its downstream IAB-nodes (e.g., IAB-node 130). The IAB-DU provides wireless backhaul to its downstream IAB-node and UE via the network functions of the NR Uu interface.

IAB-donor 110 maintains CU 112 for DUs (e.g., 121, 131) of all IAB-nodes and its own DU (111). Suppose that a DU on an IAB-node is served by only one IAB-donor in IAB architecture 100. The IAB-donor can be changed by topology adaptation. Each DU on the IAB-node is connected to a CU in the IAB-node using an F1 interface. The F1 interface operates on a backhaul RLC channel on the radio backhaul between the MT on the IAB-node and the DU on the parent IAB-node or IAB-donor. BAP sub-layers are added that hold (hold) routing information, enabling hop-by-hop forwarding.

The exemplary architecture 100 is shown as a two-hop chain of IAB-nodes below IAB-donor, where the IAB-nodes and UEs connect to the NGC in SA-mode. However, it should be understood that the IAB may support independent (SA) and non-independent (NSA) deployments. Embodiments of the present disclosure may also be implemented in an IAB architecture of NSA mode. Further, it should be appreciated that the IAB architecture 100 may be deployed with different IAB topologies. For example, the IAB-node chain may be single-hop or more than two hops. Multi-hop backhaul provides more range extension than single hop. One IAB-node may be connected to more than one upstream IAB-node or IAB-donor DU. More than one downstream IAB-node may be connected to one IAB-node or one IAB-donor DU.

Although in the exemplary architecture of fig. 1, UEs, IAB-nodes, and IAB-donors communicate via 5G, embodiments of the disclosure may also be implemented in Long Term Evolution (LTE) or LTE-advanced (LTE-a) networks, or other networks that support communication between these UEs, IAB-nodes, and IAB-donors.

The UEs 151, 152, 153 may be embodied as any suitable terminal device capable of cellular wireless communication, such as a mobile communication device, modem, cellular telephone, gaming device, navigation device, media device, laptop, desktop computer, tablet computer, smart appliance, in-vehicle communication system, or internet of things (IoT) device (such as a sensor or actuator). The IAB-nodes 120, 130 and IAB-donor may be embodied as any suitable base station supporting an IAB, such as an evolved universal terrestrial radio access network node B (E-UTRAN node B), an evolved node B, eNodeB (eNB), a next generation node B, gNode B (gNB).

The IAB technology may support both physically fixed relays (where the location of the IAB-node is fixed) and mobile relays (where the IAB-node can be mobile and its location is not fixed). For example, the IAB-node may be installed on a vehicle (such as a train, tram, or bus, etc.) to provide cellular coverage and connectivity to users or devices within the vehicle itself in different environments (e.g., for passengers in the vehicle). Such a type of IAB deployment in which an IAB node can be mobile may be referred to as a mobile IAB deployment.

Fig. 2 shows an example scenario for mobile IAB deployment, where an IAB-node is installed on a train traversing multiple coverage areas of multiple IAB-nodes. As shown in fig. 2, the IAB-node 250 (denoted as IAB 1) sequentially passes through the coverage areas (i.e., cells) of the IAB-nodes 210, 220, 230, 240. These IAB-donors may be deployed along the rails of a train. For example, some of the IAB-nodes 210, 220, 230, and 240 may be deployed on separate stops of the railway.

At a railway station, there are many stations. When different trains arrive at a train station and stop at the respective platforms, there are many UEs that will leave the respective trains or enter the respective trains. When the train arrives at the station, there may be a set of UEs (or all UEs, e.g., at the terminal) that will leave the passengers of the train. There may also be another set of UEs (or all UEs, e.g., at the origin station) that will enter the passengers of the train. When the train has one or more mobile IAB-nodes deployed to serve the UEs, the fourth type indicator indicates whether the fourth group of terminal devices indicated by the fourth group identity will not be served by the second IAB node or inside the train, and the handover will be performed for UEs leaving the train and for UEs entering the train. This may cause a large number of handovers within a short period of time. For example, during a holiday, there may be thousands of UEs entering/exiting a train at a station per day. It is a challenge for the gNB (or IAB-donor) to efficiently perform handover preparation and handover operations for such a large number of UEs.

The conventional handover of a UE is based on the detection of one or more new target cells based on UE measurements. For example, when a UE enters a car, the UE may detect a cell of a mobile IAB-node installed on a train. The UE reports information about the cell, including measured signal power, to the CU serving the UE. The CU may be a conventional gNB-CU or an IAB-donor-CU. The serving CU then initiates a handover from the external cell to the cell served by the IAB-node. For brevity, a cell serving a UE outside the vehicle is hereinafter referred to as an outside cell, and a cell serving a mobile IAB-node of a UE inside the train is referred to as an inside cell or IAB cell. Similarly, for UEs leaving the train, a handover from an inner cell to an outer cell may be performed.

Handover based on UE measurements may face some problems for mobile IAB deployments. Taking as an example a scenario where a UE enters a train (i.e. hands over from an external cell to an IAB cell). There may be a large number of UEs waiting at stations at a station and there may be a plurality of trains (equipped with corresponding mobile IAB-nodes) stopped at the station. UEs served by external cells deployed at stations may soon enter different trains (i.e., will be handed over to different mobile IAB-nodes installed on the respective trains). For a particular UE, it is not possible (and not necessary) for the serving CU to perform handover preparation to all mobile IAB-nodes. Traditionally, the serving CU knows the potential target cell based on measurement reports from the UE. But this is a challenge in deployments with mobile IABs. Due to the shielding effect of the railway car, the UE outside the train may not detect a signal for the actual target mobile IAB node of the specific UE, or the measurement report may not provide an indication that the target mobile IAB is a good target. For example, the measurement report of the UE may indicate a weak signal from an inner cell and a strong signal from an outer cell of the mobile IAB-node. Furthermore, measurement reporting may be delayed due to shielding effects and interference between different IAB-nodes.

In another scenario where the UE leaves the train (i.e., handover from an inner cell to an outer cell of the mobile IAB), there is a similar problem. The UE inside the train is served by the IAB-donor-CU, which controls the mobile IAB deployed on the train. When the train arrives at the station, some of the UEs on the train served by the IAB-node will leave the train, while other UEs will stay on the train except for the final destination. It is not possible (nor necessary) to perform handover preparation for all UEs. Only the target UE (i.e., the UE that will leave the train) needs to be handover prepared. But the serving CU (i.e. the IAB-donor-CU) has no way of knowing the target UEs, i.e. which UEs will leave the train.

Therefore, an efficient handover preparation and processing method is needed. One possible enhancement to traditional handover is the use of Conditional Handover (CHO). CHO is a handover procedure that the UE is only executed when one or more execution conditions are met. In CHO mechanism, handover preparation is performed in advance and a handover command message is sent to the UE in advance. The handover command message contains the configuration of CHO candidate cell(s) generated by the candidate gNB(s) and execution condition(s) generated by the source gNB. The UE starts evaluating the execution condition(s) after receiving the handover command message. If at least one CHO candidate cell meets the corresponding execution conditions, the UE may quickly switch to the target gNB/cell by applying the corresponding configuration stored for that selected candidate gNB/cell.

However, using CHO for the mobile IAB deployments described above is not practical. In CHO procedure, each candidate gNB/cell needs to reserve pre-configured resources in order for the UE to be able to be quickly handed over to one candidate gNB/cell after the execution conditions are met. However, for the above-described scenario of moving IABs, such as a scenario in which a large number of UEs wait to enter different trains at stations, a plurality of IAB-nodes installed on these different trains close to each other may become candidate base stations according to radio conditions. Reserving resources on each of the IAB-nodes for all UEs on the station is not possible and inefficient.

Meanwhile, several handover procedures for different situations are specified in current communication protocols, such as in the third generation partnership project (3 GPP) specifications. However, none of them support the advanced preparation of a handover of a specific target UE for deployment with mobile IABs, e.g. using CHO preparation before the UE enters (or leaves) the train. That is, the prior art mechanisms rely primarily on radio conditions.

The present disclosure proposes a solution to perform handover preparation in a mobile IAB deployment (e.g., the scenario described above) based on a handover tag indicating a set of UEs that are to be served by an IAB-node or not. The serving base station of the UE (which may be a normal gNB or IAB-donor) may receive the handover tag from the UE and the IAB-donor. The handover tag is provided to the UE in advance (e.g., at the time of purchasing a train ticket). The UE may send a handover tag to the gNB or IAB-donor before entering or exiting the train, which causes the serving base station (i.e., the gNB-CU or IAB-donor-CU) to initiate a handover-related procedure, respectively.

In some embodiments, a UE may receive at least one handover tag including a group identity (group identity) indicating a group of terminal devices to be served by an Integrated Access and Backhaul (IAB) node, or indicating a group of terminal devices not to be served by an IAB node. The UE is a member of the group of terminal devices. The group of UEs may be devices carried by passengers who have purchased tickets for the same train (or the same railway car) with the same station (outbound or inbound). For example, when a train is equipped with one IAB cell, the set of UEs may be devices carried by passengers who will take the same train with the same outbound station or will leave the same train with the same inbound station. In another example, when a train is equipped with multiple IAB cells (e.g., each railcar is equipped with one IAB cell), the set of UEs may be devices carried by passengers who will either take the same railcar with the same departure station or will leave the same train with the same arrival station. The handover tag may be provided to the corresponding UE when a passenger purchases a train ticket, or when it is detected that the UE is approaching a station or platform for a train. In this case, the ticket type may be paper, plastic, electronic ticket or application data. Of course, there will be a predefined mapping between the handover label and the target cell. For example, from a train ticket, it may be determined that a group of UEs will enter the coverage of a mobile IAB-node on the train from a particular departure station (or a particular platform thereof). Thus, the handover tag may be preconfigured to enter the coverage of the mobile-IAB node and indicate that the group of UEs is to be handed over to the target cell of the mobile-IAB node. From the train ticket, it may also be determined that a group of UEs will leave the coverage of the mobile IAB-node at a specific arrival station (or a specific station thereof). Thus, the handover tag may be preconfigured to leave the coverage of the mobile IAB-node and indicate that the group of UEs is to be handed over to the target cell of the arriving station.

In some embodiments, the UE may receive two handover labels. One handover tag includes a first group identity (group identity) indicating a first group of UEs to which the UE belongs and which are to be served by the mobile IAB-node. For example, a first group of UEs enters the same train at the same station. Another handover tag includes a second group identity (group identity) indicating a second group of UEs to which the terminal device belongs and which will not be served by the mobile IAB-node. For example, a second group of UEs leaves the same train at another same station.

In some embodiments, the UE may provide its handover tag to its serving base station (which may be a normal gNB or IAB-donor). In an example, the UE may provide a handover tag to a serving base station at a departure station, for example, when the UE enters a station and connects with the serving base station. The mobile IAB node installed on the train also provides its IAB-donor-CU with one or more handover labels, each of which comprises a group identification for a group of UEs to be served. Then, handover preparation towards a target cell of a mobile IAB-node (e.g., from IAB-donor) installed on a train parked at the station may be initiated based on a handover tag received from the UE and a handover tag received from the IAB. The procedure of handover preparation is used to establish the necessary resources in the relevant node (including target mobile IAB-node, IAB-donor, etc.).

In another example, when the train enters the station, the IAB-node of the train has migrated or connected to the IAB-node. A mobile IAB-node installed on a train provides its IAB-donor-CU with one or more handover labels, each of which includes a group identification for a group of UEs that will not be served. At this point, the UE that will leave the train may also provide a handoff tag to the IAB-donor-CU at the arrival station, e.g., when the UE approaches or arrives at the arrival station. Then, via the IAB-node, the UE served by the IAB-node may be connected to and served by the IAB-donor. Then, handover preparation from the mobile-IAB node to the target cell, which is an external cell (e.g., a cell of an IAB-donor or a cell of a normal gcb), may be initiated based on the handover tag received from the UE and the handover tag received from the IAB. The procedure of handover preparation is used to establish the necessary resources in the relevant nodes (including the external cells, CUs of the external cells, etc.).

In some embodiments, the handover tag may be provided by the UE to its serving base station (or CU) in response to a request from its base station (or CU). For example, the request may be sent to a particular UE in a unicast RRC message or in a broadcast RRC message (e.g., a System Information Broadcast (SIB)). In some embodiments, the handover tag may also be actively sent by the UE to its serving base station (or CU), e.g., without a request from the serving base station (or CU).

In some embodiments, the UE will perform a handover command after entering or leaving the coverage (or cell) of the IAB-node according to the handover preparation performed based on the handover label.

In some embodiments, a serving base station (such as a normal gNB or IAB-donor) may receive a handover tag for an IAB-node that includes a group identity indicating a group of UEs that are to be served by the IAB-node or that are not to be served by the IAB-node. In an example, the handoff tag may be received directly from the IAB-node when the serving base station is an IAB-node for the IAB node. In another example, when the serving base station is a neighboring base station of an IAB-donor for an IAB node, the handoff tag may be received from the neighboring base station as an IAB-donor for an IAB node. In this regard, the IAB-donor serving the IAB-node forwards the handoff tag to the serving base station.

In some embodiments, the serving base station may also receive a handover tag for a particular UE. The handover tag includes a group identity indicating a group of UEs that are to be served by the IAB-node or are not to be served by the IAB-node. This means that the particular UE belongs to the group of UEs.

In some embodiments, the handover tag for a particular UE may be received from the UE via an RRC message, e.g., in response to sending a request to the UE to provide the handover tag. In another embodiment, the handover tag for a particular UE may also be received from a core network, such as a 5G core network (5 GC) or evolved packet core network (EPC) or future generation core network (e.g., 6G).

Based on the handover tag received from the mobile IAB node and the handover tag received for the particular UE, the serving base station may determine whether the UE is an applicable UE for handover and a target cell for initiating handover preparation. In this regard, the serving base station may match a handover tag received for a particular UE with a handover tag received from a mobile IAB-node. For example, if the group identity indicated in the handover tag received for a particular UE matches (e.g., is included or the same as) the group identity indicated in the one or more handover tags received from the mobile IAB-node, the serving base station may determine that the particular UE is suitable for a handover involving the mobile IAB-node. This would mean that the particular UE is the applicable UE for handover, while the mobile IAB-node is the associated IAB-node to or from which the particular UE would be handed over. For example, depending on the type of handover tag, i.e., whether the handover tag is for a group of UEs to be served (e.g., UEs entering or going into coverage of a mobile IAB-node) or for a group of UEs not to be served (e.g., UEs leaving or going out of coverage of a mobile IAB-node), the serving base station may determine the direction of the handover (e.g., the handover is a handover to a mobile IAB or the handover is a handover leaving a mobile IAB), and thus may determine the target cell of the handover of the target UE. Thus, the serving base station may initiate a handover preparation for the handover. In one example, when it is a handover to a mobile IAB-node, the serving base station may be a normal base station or an IAB-node, and the handover is from an external cell to a mobile IAB cell; the serving base station may be an IAB-node when it is a handover from a mobile IAB-node, and the handover is from a mobile IAB cell to a foreign cell. The external cell and the IAB cell may belong to the same gNB-CU or different gNB-CUs.

In some embodiments, the mobile IAB-node may be configured with at least one handoff tag, e.g., for each stop of the train in the above example shown in fig. 2. For example, in the example where a mobile IAB-node is installed in a train, its switch tag for each stop indicates the respective group of UEs entering or leaving the train, that are to be switched at each of its stops. The at least one handover tag for the particular station may include a handover tag indicating a set of UEs to be served by the mobile IAB-node at the particular station (i.e., UEs that are to enter the train). This means that the group of UEs will be handed over to the mobile IAB-node. Alternatively or additionally, the at least one handover tag for the particular station may include a handover tag indicating a set of UEs to be stopped being served by the mobile IAB-node at the particular station (i.e., UEs to leave the train). This means that the group of UEs will be handed over from the mobile IAB-node at a particular station. In some other embodiments, there may be multiple IAB cells installed on the train. For example, one IAB cell is installed in each railway car. Multiple cells on a train may be served by one IAB-node or multiple IAB nodes (e.g., one cell is provided per IAB-node).

In examples where multiple cells are served by one IAB-node, the IAB-node may be configured with multiple handover labels, e.g., each IAB cell is associated with a different handover label. In yet another example, an IAB node or IAB cell may be associated with multiple sets of handover labels, e.g., one handover label for a particular set of UEs (e.g., when one IAB-node or one IAB cell is shared by multiple operators, the IAB node or IAB cell has one set of handover labels for UEs from each operator). In these examples, upon a train stop, an IAB-node may provide its IAB-donor with a plurality of handover labels, each of the plurality of handover labels including a group identification indicating a group of UEs to be served by the IAB-node. Alternatively or additionally, the IAB-node may provide its IAB-node with a plurality of handover labels, each of the plurality of handover labels including a group identity indicating a group of UEs not to be served by the IAB-node.

In some embodiments, the set of UEs indicated in the handoff tag may include one or more UEs for only one passenger (i.e., corresponding to one ticket). In other embodiments, the set of UEs indicated in the handover tag may include one or more UEs only for multiple passengers (i.e., corresponding to multiple tickets) that are to be handed over to the same target cell.

In some embodiments, the mobile IAB-node may provide its handover label to its serving IAB-donor. Taking the use case where a mobile IAB-node is installed in a train as an example, the mobile IAB-node may provide an IAB-donor at a particular station with its configured handover tag for that particular station, the handover tag including a handover tag indicating a set of UEs that will be served by the mobile IAB-node (i.e., UEs that will enter the train) when reaching the particular station, and another handover tag indicating another set of UEs that will be stopped from being served by the mobile IAB-node (i.e., UEs that will leave the train) when reaching the particular station.

In some embodiments, the mobile IAB-node or IAB-donor may also generate and send a request for a UE requiring its association to report its handover label to the serving IAB-donor. For example, when a mobile IAB-node provides an IAB-donor at a station with a handover label indicating a group of UEs to be stopped from being served by the mobile IAB-node, the mobile IAB-node may request that each UE report its own handover label to the IAB-donor. The request may be carried in a broadcast RRC message (e.g., SIB) generated by the IAB-node or by the IAB-donor. In another example, the IAB-donor of the mobile IAB-node may request that each UE report its own handover tag to the IAB-donor. The request may be carried in a unicast RRC message generated by the IAB-donor. In yet another example, the IAB-donor may receive a handover tag of the UE when the UE is handed over from its serving base station to the IAB-donor, e.g., when the UE is handed over from an external cell to an IAB cell, or when the UE is handed over from a first IAB-donor to a second IAB-donor during an IAB migration from the first IAB-donor to the second IAB-donor.

In this way, the present disclosure may support advanced handover of a UE from/to a cell of a mobile IAB-node. FIG. 3 shows an example call flow for the proposed solution. This example may be implemented in the scenario shown in fig. 2.

It is assumed that there are two rail stations along the rail of the train. IAB1 250 is an IAB-node installed on a train. IAB-donor1 210 serves the first rail station, and DU1 211 is a DU of IAB-donor1 210 for providing the external cell #1.IAB-donor4 240 serves the second rail station, and DU2 241 is the DU of IAB-donor4 240 for providing the external cell #2. It is assumed that there is the same CU for the IAB-node at the outer cell and the station. For example, CU1 212 controls external cell #1 and acts as an IAB-donor-CU for IAB1 250 at the first station, while CU2 241 controls external cell #2 and acts as an IAB-donor-CU at the second station.

At the first rail station, a terminal device (e.g., UE) UE1 301 may connect with an external cell #1 of DU1 211, as shown in step 310. For example, UE1 may stay at a first train station or its station.

The IAB1 250 is installed in a train. According to a train ticket, the user of UE1 will take the train. The IAB1 250 may be coupled to the IAB-donor 1210 as shown in step 315, for example, when the train approaches the first rail station, or after the train reaches the first rail station. At this point, IAB1 250 may inform CU1 212 that it will begin serving UEs belonging to a particular group identified by Enter-ID #E1 (e.g., referred to as Enter-group). In this regard, IAB1 250 may send a switch label (e.g., a third switch label) to CU1 212 that includes a group identification (e.g., a third group identification) (e.g., enter-ID #e1 indicating a particular group). In addition, IAB1 250 may also inform CU1 212 that it will cease servicing UEs belonging to another specific group identified by Leave-ID #L1 (e.g., referred to as Leave-group). In this regard, the IAB1 250 may send another switch label (e.g., a fourth switch label) to the CU1 212 that includes another specific group identification (e.g., a fourth group identification) (e.g., a Leave-ID #l1 indicating the other specific group). It is envisioned that if the first rail station is the originating station, there may not be a UE belonging to Leave-group. Then the Leave-group may be empty or IAB1 250 may only notify CU1 212Enter-group and not notify Leave-group. The operations of step 315 may be implemented via an F1 application protocol (F1 AP) procedure (e.g., as defined in 3GPP specification TS 38.473) or an RRC procedure (e.g., as defined in 3GPP specification TS 38.331).

The IAB-node may be supplied with information for the Enter-Group and Leave-Group of each station where the train will stop. In some examples, an IAB-node may have multiple cells installed at different railcars; each cell may be associated with a specific Enter-ID. For example, the low 4 bits of the Enter-ID may identify one of a total of 16 cells installed on the train. Alternatively, the Enter-ID may comprise the cell ID of the cell of the IAB node. The number of bits is merely an example, and may be changed according to the capacity of a specific station.

In some embodiments, IAB1 250 may determine that the train will arrive (or has arrived) at a particular stop based on the location of the train. In further embodiments, IAB1 250 may be connected to a train on-board computer such that information about stops, speeds, arrivals, and departure may be transferred to IAB1 250.

In the present disclosure, the Enter-ID and Leave-ID are included in the Enter-type tag and Leave-type tag, respectively, commonly referred to as a "switch tag" (also referred to as a "tag"). An example of the structure for switching the tag is shown in table 1, which will be described in detail later.

The IAB-donor1 210 may request that the UE served by the IAB-donor1 210 provide its handover tag. As shown in step 320, CU1 212 may send a message requesting UE1 301 to provide its handover tag (e.g., enter-Type tag). When UE1 is served by cell #1 of CU1, the message is delivered to UE1 301 via DU1 211. In one example, the request for a handover tag may be triggered when UE1 connects with cell #1, and/or when a new Enter-type tag (e.g., including a new Enter-ID) is received from IAB1 250 (e.g., when its train has just arrived at the station). In yet another embodiment, DU1 may generate SIBs that require the UE to report its handover tag.

As shown in step 325, UE1 301 may provide CU1 212 with an Enter-type switch tag (e.g., a first switch tag) that includes a group identification (e.g., a first group identification, such as an Enter-ID) for the first station. The UE1 301 may be previously supplied with two handover tags (i.e., an Enter-type tag and LEAVE TYPE tag). In one example, when the user of UE1 301 purchases a train ticket via a UE application installed on UE1 301, the two handover labels may be configured and provided to UE1 301, e.g., by an operator. It should be appreciated that a user may have multiple communication devices (e.g., mobile phone, tablet, wearable device, etc.). In this case, the same handover label may be provided for all users' communication devices. In this example, assume that the user of UE1 301 starts the journey at a first stop and stops the journey at a second stop. Thus, for UE1 301, the Enter-type tag includes Enter-ID #E1 and the Leave-type tag includes Leave-ID #L2.

In some embodiments, an Enter-type switch tag may be sent from UE1 301 to CU1 212 at step 325 in response to receipt of a request from CU1 212. In other embodiments, UE1 301 may send at least one of its switch labels (e.g., an Enter-type switch label including an Enter-ID, a Leave-type switch label including a Leave-ID) to CU1 212 without a request from CU1 212. For example, during the RRC establishment procedure, UE1 301 may provide its at least one handover tag to CU1 212. CU1 212 then saves the information as part of the UE context of UE1 301.

As shown in step 330, CU1 may determine an applicable UE for handover and a target cell for the applicable UE(s) based on the at least one handover tag received from the corresponding UE and the at least one handover tag received from IAB1 250. In this regard, based on the Enter-ID received from UE1 301 and the Enter-ID received from IAB1 250, CU1 212 may determine that UE1 301 is one of the applicable UEs, i.e., UE1 301 needs to be handed over to IAB1 250. For example, CU1 may check whether the first handover tag (including the first group identification) received from UE1 301 matches the third handover tag (including the third group identification) received from IAB1 250. If there is a match, e.g., the two Enter-IDs are identical to each other (e.g., both are #e1), it may be determined that UE1 301 is to be switched to IAB1 250. In one example, based on the Enter-ID received from IAB1 250, CU1 212 may determine a target cell for a group of UEs having the same Enter-ID #e1. In another example, the target cell may be determined based on the Enter-ID from UE1 301.

It should be noted that this process does not require CU1 212 to use measurement reports from the UE (e.g., UE 1) to determine that the UE is to be handed over. It may not be appropriate to require all UEs staying at the first station to perform measurement reporting, especially when the measurement reporting of the UE may not provide a correct indication. For example, the measurement report of the UE may indicate a weak signal from IAB1 250 due to the train's window covering.

CU1 212 may then initiate a handover or conditional handover procedure for the determined applicable UE (e.g., UE1 301). In this example, CU1 212 may initiate a preparation procedure for a handover or conditional handover of UEs in the same Enter group (identified as #e1), and the target cell is the cell of IAB1 250, as shown in step 335. This preparation procedure is used to establish the necessary resources in IAB1 250 and IAB-donor1 210 for handover.

Next, UE 1250 may perform a handover and connect with IAB1250 (through the DU of IAB 1250). In an example, when UE1 301 enters a railway car, UE1 301 may execute a handover command. For example, UE1 301 may send RRCReconfigurationComplete a message to IAB1250 to indicate that the handover procedure is complete, as shown in step 340. IAB1250 may forward the message to CU1 212.UE 1250 is now served by IAB1250 and IAB-donor 1.

As the train travels along the railway line, it moves to the second rail station in the coverage of IAB-donor4 240. IAB1250 may migrate to IAB-donor4 240 as shown in step 345. Similar to step 315, IAB1250 may inform CU2 242 that it will cease servicing UEs belonging to another specific group identified by Leave-ID #L2 (e.g., referred to as Leave-group). In this regard, the IAB1250 may send a switch label (e.g., a third switch label) to the CU2 242 that includes a group identification (e.g., a third group identification) (e.g., leave-ID #l2 indicating a specific group). In addition, IAB1250 may also inform CU2 242 that it will begin serving UEs belonging to a particular group identified by Enter-ID #E2 (e.g., referred to as Enter-group). In this regard, IAB1250 may send another switch label (e.g., a fourth switch label) including the group identification (e.g., a fourth group identification) (e.g., enter-ID #e2 indicating the other specific group) to CU2 242. It is foreseen that if the second rail station is the final station, there may not be a UE belonging to the Enter-group. Then the Enter-group may be empty or IAB1250 may only notify CU2 242Leave-group and not notify the Enter-group. The operations of step 345 may be implemented via an F1AP procedure (e.g., as defined in 3GPP specification TS 38.473) or an RRC procedure (e.g., as defined in 3GPP specification TS 38.331). When IAB1250 is migrated to CU2 (e.g., just before the train arrives at the second rail station), or later after the migration (e.g., when the train is approaching the second rail station), IAB1250 may perform the notification process of step 345. During the notification process (step 345), IAB1 205 notifies CU2 that it will serve UE group #e2 and stop serving UE group #l2.

In some embodiments, IAB-donor4 240 may request the UEs to provide their at least one handover tag. As shown in step 350, CU2 242 sends a message requesting UE1 to provide its at least one handover label (e.g., including a Leave-ID). When UE1 is served by the inner cell of IAB1, the message is delivered to UE1301 via the DU (not shown) of IAB1 250. In an example, the request may be triggered if CU2 242 detects that IAB1 250 is approaching a second station, or may be triggered by an indication from IAB1 250 when IAB1 250 detects that it is approaching a second station.

In some other embodiments, IAB1 250 may generate and send (e.g., through its DU) a request that UEs within its coverage provide their handover labels. For example, a DU (not shown) of IAB1 250 may generate a SIB owned by the DU, ask the UE to provide its handover tag including the Leave-ID, and send the SIB to the UE when the train is approaching the second station or before approaching.

As shown in step 355, UEl provides its Leave-type tag (e.g., a second group identification) to CU2 242, which includes a group identification (e.g., a second group identification), such as Leave-ID #L2. In some embodiments, only UEs that will Leave the train at the second station (i.e., leave IAB1 250) will provide their corresponding Leave-type tags.

In some other embodiments, the UE may send its handover tag (e.g., including Leave-ID) by using some predefined condition without an explicit request from the network. For example, the UE may send its handover tag (e.g., including Leave-ID) using some predefined condition without an explicit request from the network. In an example, the UE may detect that it is approaching/entering a train station and responsively send its handoff tag (e.g., including a Leave-ID). In another example, the UE may detect a cell served by IAB-donor4 and find its cell ID identical to the cell ID indicated by its handover tag and then report its handover tag (e.g., including the Leave-ID).

In further embodiments, once UE1 301 connects to the cell of IAB1 250, UE1 may provide its handover tag (e.g., including a Leave-ID). In an example, a handover tag (e.g., including a Leave-ID) may be integrated into the UE context such that the handover tag (e.g., including a Leave-ID) may be transmitted on an Xn interface between neighboring CUs. Thus, instead of requesting UE1 301 to transmit a handover tag (e.g., including a Leave-ID), the handover tag (e.g., including a Leave-ID) may be exchanged between CUs of the IAB-donor and/or the gNB. For example, the context of UE1 may be transferred from IAB-donor1 to IAB-donor4. This embodiment may be valid for the case where the handover tag (e.g. comprising an Enter-ID and/or Leave ID) is preconfigured, e.g. by an operator of the communication system.

CU2 242 can then determine the applicable UE and the target cell(s) for the applicable UE for handover based on the at least one handover tag received from the corresponding UE and the at least one handover tag received from IAB1 250. In this regard, based on the handover tag (including the Leave-ID) received from UE1 301, CU2 242 may determine that UE1 301 is one of the applicable UEs, i.e., UE1 301 needs to be handed over from an inner cell (e.g., the cell of IAB1 250) to an outer cell (e.g., the cell of IAB-donor1 240). For example, CU2 242 may check whether the second handover label (including the second group identification) received from UE1 301 matches the fourth handover label (including the fourth group identification) received from IAB 1250. If there is a match, e.g., the two Leave-IDs are identical to each other (e.g., both Leave-IDs are #L2), it may be determined that UE1 301 is to be handed over from IAB1250, e.g., to the target cell of IAB-donor1 240 (denoted as external cell # 2).

In an example, the target cell may be determined at CU2 242, e.g., based on a preconfigured mapping from Leave-IDs to external cells. In another example, the target cell may be determined based on measurement reports of MT(s) (not shown) of IAB1 250. For example, when the train enters the second station, IAB1 250 may perform measurements (via its MT (s)) on the external cells (e.g., including external cell # 2) of IAB-donor 4240.

CU2 242 may then initiate a handover or conditional handover procedure for the determined applicable UE (e.g., UE1 301). In this example, CU2 242 may initiate a handover or conditional handover preparation procedure from IAB1250 to target cell #2 for UEs in the same Leave group (identified as #l2), as shown in step 365. This preparation procedure is used to establish the necessary resources in DU2 241 and CU2 242 for handover.

Next UEl a 301 can perform the handover and connect with DU2 of IAB-donor 240. In an example, UEl 301 may execute a switch command when UEl 301 leaves the train. For example, UE1 301 may send RRCReconfigurationComplete a message to DU2 241 to indicate that the handover procedure is complete, as shown in step 370. DU2 241 may forward the message to CU2 242.UE1 250 is now served by the external cell (i.e., the cell of DU2 241) and CU2 242.

It should be appreciated that for UEs that will Enter the covered Enter group # e2 of IAB1 250 at the second station, IAB-donor4 240 may handle their mobility from an external cell (e.g., the cell of DU2 241) to an internal cell (e.g., the cell of IAB1 250) to similar procedures to those performed in steps 310-340. Similarly, for UEs that will Leave the covered Leave group #l1 of IAB1 250 at the first station, IAB-donor1210 may handle their mobility from an inner cell (e.g., the cell of IAB1 250) to an outer cell (e.g., the cell of DU1 211) to procedures similar to those performed in steps 345 to 370.

An example structure for switching labels is shown in table 1.

TABLE 1 Structure of switch Label

1. The tag type indicates the type of the handover tag, i.e., whether the UE group (group ID) will be served by the IAB-node (e.g., having a value of "1" of one bit) or will not be served by the IAB-node (e.g., having a value of "0" of one bit).

2. Alternatively, the handover tag may have an identification of the cell (i.e. cell ID) used for the handover, which may be, for example, an NR Cell Global Identifier (CGI). It indicates that +.

The IAB cells serving a group of UEs identified by the group ID are stopped.

3. A group ID (identity) indicating a group of UEs that will be served by the IAB-node or will not be served by the IAB-node. For a handover tag of a particular UE, it explicitly indicates that the particular UE belongs to the group. For a handover label of a particular IAB node, it explicitly indicates whether the particular UE group is to be served by an IAB cell of the particular IAB or is not to be served by an IAB cell of the particular IAB.

4. Alternatively, the switch tag may have an expiration timer that indicates when the switch tag will expire. If the switch tag is not used, the timer may be utilized to delete the switch tag after a period of time.

The group ID may be defined for each IAB-node. In the example discussed above with reference to fig. 3, group IDs may be defined per train and per rail station. For example, a portion of bits of the Group ID may be mapped to a train number and another portion of bits of the Group ID may be mapped to a rail station number. In some embodiments, the cell ID may be mapped to a group ID. For example, the group ID includes a train number and a cell ID of an IAB cell installed on the train. Thus, the cell ID may be derived from the group ID. In this example, the cell ID need not be included in the handover tag.

In some scenarios, an inner cell (e.g., an IAB-node cell) and an outer cell may belong to two different CUs. At least one switch label may be exchanged between two CUs, for example, over an Xn interface. Fig. 4 shows an exemplary procedure for mobility processing of such a scenario, which may be regarded as a variant of the procedure shown in fig. 3.

The variation is that at the first station, IAB1 250 may be connected to IAB-donor6 260, IAB-donor6 260 being different from the gNB (e.g., gNB1 270) controlling the foreign cell # 4. In one embodiment, gNB may be IAB-donor. The IAB1 250 may then send information for the handoff tag of the first station to CU3 262 of the IAB-donor6 260. As shown in step 415A, IAB1 250 may inform CU3 262 that it will start serving UEs belonging to a specific group identified by Enter-id#e1 (e.g., referred to as Enter-group). In addition, IAB1 250 may also inform CU3 262 that it will cease servicing UEs belonging to another specific group identified by Leave-ID #L1 (e.g., referred to as Leave-group). CU3 262 may then inform its neighboring CUs of the switch label. As shown at 415B, CU3 262 may send a switch label to CU4272 indicating that IAB1 will service group #e1 and will stop service group #l1.

In another embodiment, IAB1 250 is connected with IAB-donor6 260, while UE1 301 is served by a common gNB (e.g., gNB1 270), such as when UE1 301 is at a rail station or the like. In this case, CU3 262 can forward the handover label of IAB1 250 to the normal gNB (e.g., its gNB-CU). The gNB may also receive a handover tag for UE1 301. Then, based on the handover tag from IAB-donor6 260 and the handover tag from UE1 301, the gNB may initiate a handover from its cell (the outer cell) to IAB1 250.

The operations at steps 410, 420, 425, 430, 435, and 440 may be similar to steps 310, 320, 325, 330, 335, and 340, respectively, shown in fig. 3.

In some embodiments, the IAB-donor may obtain at least one handover tag for the UE from a core network (such as 5GC or EPC). For example, at least one handoff tag is available in 5GC, where the Application Function (AF) may provide relevant information to the Policy Control Function (PCF) directly or via the Network Exposure Function (NEF). Information about at least one handover label for the UE may be provided to an Access and Mobility Function (AMF) via an AF or PCF. The NG-RAN node may obtain at least one handover tag for the UE from the AMF.

Fig. 5 shows an exemplary procedure of mobility processing according to such an embodiment, which may be regarded as another variant of the procedure shown in fig. 3. That is, for the procedure in which UE1 enters the coverage of IAB1, steps 510, 515, 530, 535, and 540 in fig. 5 are accordingly the same as corresponding steps 310, 315, 330, 335, and 340 in fig. 3. The variation is that steps 320 and 325 in fig. 3 are changed to perform steps 520A and 525A, or steps 520B and 525B, between CUs 1 and 5 GC. The variation of such embodiments is similar for the procedure in which UE1 leaves the coverage of IAB 1. For simplicity, fig. 5 only shows the procedure for UE1 to enter the coverage of IAB 1.

In one example, AMF 501 may provide UEl at least one switch label (e.g., including an Enter-ID) to CU1 212, as shown in step 525A, e.g., during an N2 procedure that provides UE context to CU1 212. N2 is the interface between the AMF and the RAN node. In another example, CU1 212 may send a request (e.g., an N2 request) to AMF 501 to provide at least one handover tag (e.g., including an Enter-ID) for UE1, as shown in step 520A, and in response, CU1 212 may receive the handover tag (e.g., including an Enter-ID #e1) from AMF 501 at step 525A. For example, when CU1 212 receives a switch tag (e.g., including an Enter-ID) from IAB1 250, an N2 request may be sent. Thus, the switch tag information is obtained from 5 GC.

In another example, the at least one handover tag may be part of the UE context. In this regard, during an associated UE context setup or modification procedure, the 5GC (e.g., AMF 501) provides UE context of a particular UE to the RAN node, including a handover tag of the particular UE.

In further embodiments, a Location Management Function (LMF) may provide handover labels of a list of UEs related to a handover scenario of a mobile IAB to an IAB-donor directly or indirectly via other core network nodes (e.g., AMFs). In an example, the UEs in the list may be UEs in the vicinity of the first train or on a platform of the first station. For example, as shown in step 520B, CU1 121 may request that LMF 502 provide a handover label for the UE list. For example, the list of UEs may be denoted UE1, UEi, UEj … …. The LMF 502 may then provide at least one handoff tag of the UE list, including their Enter-ID { #e1, #ei, #ej, … … } and/or Leave-ID { #l1, #li, #lj, … … }, as shown in step 525B. This embodiment has the advantage of reducing the signalling overhead with respect to requesting handover labels for multiple UEs. This is particularly relevant for obtaining a handover tag for a UE entering a train. In contrast, to obtain the handover label of the UE leaving the train, the UE is already connected to the IAB1 250 and the signaling overhead is not too heavy.

With embodiments of the present disclosure, handover of UEs entering/exiting a train can be prepared in advance without requiring measurement reports from the respective UEs. Thus, mobility handling of the UE may be performed efficiently and accurately, especially when measurement reports from the UE may provide an incorrect indication.

Referring now to fig. 6, a flow chart of a method 600 according to an embodiment of the present disclosure is shown. The method may be performed at the UE, for example by UE 1301 as shown in fig. 3 and 4. Alternatively, the method may be performed at a core network entity, such as AMF 501 and LMF 502, as shown in fig. 5.

As shown in block 610, the method 600 includes: at least one handover tag for a terminal device is obtained, the at least one handover tag comprising a first group ID indicating a first group of terminal devices (e.g. UEs) to be served by an IAB node, or comprising a second group ID indicating a second group of terminal devices not to be served by an IAB node. At block 620, the method 600 includes: at least one handover tag is transmitted to at least one base station (such as the gNB, IAB-donor, e.g., IAB-donor1210, IAB-donor4 240 as shown in FIGS. 3,4 and 5) such that a procedure related to a handover of a terminal device to or from an IAB node can be initiated by the at least one base station based at least in part on the at least one handover tag.

In some embodiments, the at least one handover tag may include a first handover tag (e.g., including an Enter-ID) for the terminal device that indicates a first group of terminal devices to be served by an IAB node, such as an IAB node, e.g., IAB1 250 shown in fig. 3, 4, 5. Transmitting the at least one handover tag to the at least one base station may include transmitting a first handover tag to a first base station (e.g., gNB, IAB-donor1, 210) of the at least one base station such that a procedure related to a handover of the terminal device to the IAB node can be initiated based at least in part on the first handover tag.

In some embodiments, the at least one handover tag includes a second handover tag (e.g., including a Leave-ID) for the terminal device indicating a second group of terminal devices that are not to be served by the IAB node. Transmitting the at least one handover tag to the at least one base station may include transmitting a second handover tag to a second base station (e.g., gNB, IAB-donor1 210, IAB-donor4 240) of the at least one base station such that a procedure related to a handover of the terminal device from the IAB node can be initiated based at least in part on the second handover tag.

In some embodiments, the method 600 may further include receiving a request for at least one handoff tag from at least one base station. The at least one handoff tag may then be transmitted in response to the request for the at least one handoff tag.

In some embodiments, the at least one handoff tag may be transmitted without a request from the at least one base station.

In embodiments where the method 600 is performed at a location management function (e.g., LMF 502), the method 600 may further include transmitting a set of handover labels to at least one base station, the set of handover labels including a plurality of handover labels for a plurality of terminal devices. The set of handover labels includes at least one handover label for the terminal device.

Fig. 7 is a flow chart depicting a method 700 according to an embodiment of the present disclosure. The method may be performed at an IAB-donor or at a common base station, e.g., by the gNB1 270, IAB-donor1 210 or IAB-donor4 240 as shown in fig. 3, 4 and 5.

As shown in block 710, the method 700 includes: at least one handoff tag of a first IAB node (such as IAB node, e.g., IAB1 250) is received. The at least one handover tag includes a third group ID indicating a third group of terminal devices (e.g., UEs) to be served by the first IAB node or includes a fourth group ID indicating a fourth group of terminal devices not to be served by the first IAB node. At block 720, method 700 includes: at least one handover tag for a terminal device (e.g., UE1 301 shown in fig. 3,4, and 5) is received that includes a first group ID indicating a first group of terminal devices to be served by a second IAB node or a second group ID indicating a second group of terminal devices not to be served by the second IAB node. At block 730, the method 700 includes: at least one handover tag of the first IAB node is matched with at least one handover tag for the terminal device. At block 740, the method 700 includes: a procedure related to a handover of the terminal device to or from the first IAB node is initiated based at least in part on a match of at least one handover tag of the first IAB node with at least one handover tag for the terminal device. In an example, method 700 can include preparing to initiate a handoff of a terminal device.

In some embodiments, at least one handoff tag in the first IAB node is received from the first IAB node. In other embodiments, at least one handoff tag of the first IAB is received from another base station.

In some embodiments, at least one handoff tag for a terminal device may be received from the terminal device. In other embodiments, at least one handover tag for the terminal device may be received from the core network node.

The method 700 may further comprise sending a request to the terminal device or the core network node for at least one handover tag for the terminal device. The received at least one handover tag for the terminal device may be transmitted in response to the request.

In some embodiments, at least one handover tag for a terminal device may be received from another base station controlling an IAB node. In some embodiments, the at least one handover tag for the terminal device may be received from the source base station during a handover procedure performed from the source base station to a current serving base station for the terminal device.

In some embodiments, matching the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device may include at least one of: determining whether the first group ID is included in the third group ID or is the same as the third group ID; or whether the second group ID is included in the fourth group ID or is the same as the fourth group ID.

In some embodiments, matching the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device may further comprise at least one of: determining that the handover of the terminal device is a handover to the first IAB node when the at least one handover tag of the IAB node indicates that the third group of terminal devices will be served by the first IAB node and the at least one handover tag for the terminal device indicates that the first group of terminal devices will be served by the second IAB node; and determining that the terminal device is handed over from the first IAB node when the at least one handover tag of the first IAB node indicates that the fourth group of terminal devices will not be served by the first IAB node and the at least one handover tag for the terminal device indicates that the second group of terminal devices will not be served by the second IAB node.

In some embodiments, the method 700 may further comprise: determining a target cell for handover based on at least one handover tag of the first IAB node and/or at least one handover tag for the terminal device; and determining that the terminal device is an applicable terminal device for handover based on at least one handover tag of the first IAB node and/or at least one handover tag for the terminal device.

Fig. 8 is a flow chart depicting a method 800 according to an embodiment of the disclosure. The method may be performed at an IAB node, for example, by IAB1 250 as shown in fig. 3, 4 and 5.

As shown in block 810, the method 800 includes: at least one handover tag of the IAB node is obtained comprising a third group identity indicating a third group of terminal devices (such as UEs) to be served by the IAB node or comprising a fourth group identity indicating a fourth group of terminal devices not to be served by the IAB node.

At block 820, method 800 includes transmitting at least one handover tag of an IAB node to an IAB donor (such as IAB-donor, e.g., IAB-donor1 and IAB-donor4, as shown in fig. 3, 4, 5) such that a procedure can be initiated based at least in part on the at least one handover tag. The procedure is related to a handover of a terminal device of the third group of terminal devices or the fourth group of terminal devices to or from an IAB node.

In some embodiments, the at least one handover tag may include a third handover tag indicating a third group of terminal devices to be served by the IAB node. The third handoff tag may be sent to an IAB donor, which may forward the third handoff tag to other base stations, such that a process can be initiated based at least in part on the third handoff tag.

In some embodiments, the at least one handover tag may include a fourth handover tag indicating a fourth group of terminal devices that are not to be served by the IAB node. The fourth handoff tag is sent to the IAB donor, which may forward the fourth handoff tag to the other base station such that the process can be initiated based at least in part on the fourth handoff tag.

The method 800 may further include sending a request to the terminal device for reporting at least one handover tag for the terminal device to the IAB donor, wherein the at least one handover tag for the terminal device includes a first group identification indicating a first group of terminal devices to be served by the IAB node or includes a second group identification indicating a second group of terminal devices not to be served by the IAB node.

In some embodiments, the method 800 may further include receiving at least one handoff tag for a terminal device from the terminal device, wherein the at least one handoff tag for the terminal device includes a first group identification indicating a first group of terminal devices to be served by the IAB node or includes a second group identification indicating a second group of terminal devices not to be served by the IAB node; and forwarding at least one handover label for the terminal device to the IAB donor.

In some embodiments, at least one handoff tag of an IAB node may be sent to an IAB donor when the IAB node is connected to the IAB donor.

Referring now to fig. 9, fig. 9 shows a simplified block diagram of an apparatus 900, which apparatus 900 may be embodied in/as a data processing device (such as a UE, IAB-node, IAB-done, as shown in fig. 3, 4, 5). The apparatus 900 may include at least one processor 901, such as a Data Processor (DP), and at least one memory (MEM) 902 coupled to the at least one processor 901. The apparatus 900 may also include one or more transmitters TX, one or more receivers RX 903, or one or more transceivers coupled to the one or more processors 901 to communicate wirelessly and/or through wires.

Processor 901 may be of any type suitable to the local technical environment and may include, as non-limiting examples, one or more of the following: general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs), and processors based on a multi-core processor architecture.

The MEM 902 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory, as non-limiting examples.

The MEM 902 stores a Program (PROG) 904.PROG 904 may include instructions that, when executed on an associated processor 901, enable apparatus 900 to operate in accordance with embodiments of the present disclosure, such as performing one of methods 600, 700, and 800. The combination of the at least one processor 901 and the at least one MEM 902 may form a processing circuitry or component 905 suitable for implementing various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented by computer programs executable by one or more of the processor 901, software, firmware, hardware, or a combination thereof.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

Accordingly, it should be understood that at least some aspects of the exemplary embodiments of this invention may be practiced in various components, such as integrated circuit chips and modules. It should thus be appreciated that exemplary embodiments of the invention may be implemented in an apparatus embodied as an integrated circuit, wherein the integrated circuit may include circuitry (and possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry, and radio frequency circuitry, which is configurable to operate in accordance with exemplary embodiments of the invention.

It should be understood that at least some aspects of the exemplary embodiments of this invention may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer-executable instructions may be stored on a computer-readable medium, such as a non-transitory computer-readable medium, such as a hard disk, an optical disk, a removable storage medium, a solid state memory, RAM, or the like. As will be appreciated by those skilled in the art, the functionality of the program modules may be combined or distributed as desired in various embodiments. In addition, the functionality may be embodied in whole or in part in firmware or hardware equivalents such as integrated circuits, field Programmable Gate Arrays (FPGA), and the like.

As used in this disclosure, the term "circuitry" may refer to one or more or all of the following:

(a) Hardware-only circuit implementations (such as implementations in analog and/or digital circuitry only) and

(B) A combination of hardware circuitry and software, such as (as applicable):

(i) Combination of analog and/or digital hardware circuit(s) and software/firmware, and

(Ii) Any portion of the hardware processor(s) (including digital signal processor (s)), software, and memory(s) with software that work together to cause a device (such as a mobile phone or server) to perform various functions and

(C) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or portion of microprocessor(s), that require software (e.g., firmware) to operate, but may not exist when software is not required for operation.

This definition of "circuitry" applies to all uses of this term in this disclosure, including in any claims. As a further example, as used in this disclosure, the term "circuitry" also encompasses hardware-only circuitry or processor (or multiple processors) or a portion of hardware circuitry or processor and its (or their) implementation in conjunction with software and/or firmware. The term "circuitry" also encompasses, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure.

The invention includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this invention will become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this invention.

Claims (37)

1. An apparatus for wireless communication, the apparatus comprising:

At least one processor; and

At least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:

Obtaining at least one handover tag for a terminal device, the at least one handover tag comprising: a first group identity indicating a first group of terminal devices to be served by an Integrated Access and Backhaul (IAB) node, or comprising: a second group identity indicating a second group of terminal devices not to be served by the IAB node; and

The method further includes transmitting the at least one handover tag to at least one base station such that a procedure related to a handover of the terminal device to or from the IAB node can be initiated by the at least one base station based at least in part on the at least one handover tag.

2. The apparatus of claim 1, wherein the at least one handoff tag comprises a first handoff tag for the terminal device, the first handoff tag indicating the first group of terminal devices to be served by the IAB node, and

Wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to:

the method further includes transmitting the first handoff tag to a first base station of the at least one base station such that a procedure related to handoff of the terminal device to the IAB node can be initiated based at least in part on the first handoff tag.

3. The apparatus of claim 1 or 2, wherein the at least one handover tag comprises a second handover tag for the terminal device, the second handover tag indicating the second group of terminal devices that are not to be served by the IAB node, and

Wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to:

the method further includes transmitting the second handover tag to a second base station of the at least one base station such that a procedure related to handover of the terminal device from the IAB node can be initiated based at least in part on the second handover tag.

4. The apparatus of claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to,

A request for the at least one handoff tag is received from the at least one base station,

Wherein the at least one handoff tag is transmitted in response to the request for the at least one handoff tag.

5. The apparatus of claim 1, wherein the at least one handoff tag is transmitted without the request from the at least one base station.

6. The apparatus of claim 3, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to transmit the second handoff tag by at least one of:

When the terminal equipment is switched to the second base station, sending the second switching label to the first base station so as to forward the second switching label to the second base station;

after detecting that the terminal equipment is located near the second base station, sending the second switching label to the second base station; and/or

And after the terminal equipment detects the cell served by the second base station, the second handover label is sent to the second base station.

7. The apparatus according to any of claims 1 to 6, wherein the apparatus is comprised in the terminal device.

8. The apparatus according to any of claims 1 to 6, wherein the apparatus is comprised in a core network node.

9. The apparatus of claim 8, wherein the core network node comprises access and mobility functions.

10. The apparatus according to any of claims 7 to 9, wherein the first and/or second handover label is transmitted in the context of the terminal device.

11. The apparatus according to claim 8 or 9, wherein the core network node comprises a location management function, and wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to:

Transmitting a handover tag set comprising a plurality of handover tags for a plurality of terminal devices to the at least one base station,

Wherein the set of handover labels comprises the at least one handover label for the terminal device.

12. The apparatus of any of claims 1 to 11, wherein the at least one switch tag further comprises at least one of:

A first type indicator indicating whether the first group of terminal devices indicated by the first group identity are to be served by the IAB node; or alternatively

A second type indicator indicating whether the second group of terminal devices indicated by the second group identity is to be served by the IAB node.

13. The apparatus of claim 12, wherein the at least one handoff tag further comprises:

Identification of the cell; and/or

An expiration time of the at least one handoff tag.

14. An apparatus for wireless communication at a base station, the method comprising:

At least one processor; and

At least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:

Receiving at least one handoff tag of a first Integrated Access and Backhaul (IAB) node, the at least one handoff tag comprising: a third group identity indicating a third group of terminal devices to be served by the first IAB node, or comprising: a fourth group identity indicating a fourth group of terminal devices not to be served by the first IAB node;

Receiving at least one handover tag for a terminal device, the at least one handover tag comprising: a first group identity indicating a first group of terminal devices to be served by a second IAB node, or comprising: a second group identity indicating a second group of terminal devices not to be served by a second IAB node;

Matching the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device; and

A procedure related to a handover of the terminal device to or from the first IAB node is initiated based at least in part on a match of the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device.

15. The apparatus of claim 14, wherein the at least one handoff tag of the first IAB node is received from the first IAB node or from another base station.

16. The apparatus of claim 14 or 15, wherein the at least one handover tag for the terminal device is received from at least one of:

A terminal device;

A core network node; or alternatively

And an additional base station.

17. The apparatus according to any of claims 14 to 16, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to:

transmitting a request to the terminal device or the core network node for the at least one handover tag for the terminal device,

Wherein the received at least one handover tag for the terminal device is sent in response to the request.

18. The apparatus according to any of claims 14 to 17, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to match the at least one handover tag of the first IAB with the at least one handover tag for the terminal device by at least one of:

determining whether the first group identity is included in the third group identity or is the same as the third group identity; or alternatively

Determining whether the second group identity is included in the fourth group identity or is the same as the fourth group identity.

19. The apparatus of claim 18, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to match the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device by at least one of:

Determining that the handover of the terminal device is to be a handover to the first IAB node when the at least one handover tag of the first IAB node indicates that the third group of terminal devices is to be served by the first IAB node and the at least one handover tag indicates that the first group of terminal devices is to be served by the second IAB node; or alternatively

Determining that the handover of the terminal device is a handover from the first IAB node when the at least one handover tag of the first IAB node indicates that the fourth group of terminal devices will not be served by the first IAB node and the at least one handover tag for the terminal device indicates that the second group of terminal devices will not be served by the second IAB node.

20. The apparatus according to any of claims 14 to 18, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to match the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device by:

Determining a target cell for the handover based on the at least one handover tag of the first IAB node and/or the at least one handover tag for the terminal device; and

Determining that the terminal device is an applicable terminal device for the handover based on the at least one handover tag of the first IAB node and/or the at least one handover tag for the terminal device.

21. The apparatus of any of claims 14-20, wherein the at least one handoff tag of the first IAB node further comprises:

A third type indicator indicating whether the third group of terminal devices indicated by the third group identity is to be served by the first IAB node; or alternatively

A fourth type indicator indicating whether the fourth group of terminal devices indicated by the fourth group identity will not be served by the first IAB node; and

Wherein the at least one handover tag for the terminal device further comprises:

a first type indicator indicating whether the first group of terminal devices indicated by the first group identity is to be served by the second IAB node; or alternatively

A second type indicator indicating whether the second group of terminal devices indicated by the second group identity will not be served by the second IAB node.

22. The apparatus of claim 21, wherein at least one of the at least one handover tag of the first IAB node or the at least one handover tag for the terminal device further comprises:

Identification of the cell; and/or

An expiration time of the at least one handover tag of the first IAB node or the at least one handover tag for the terminal device.

23. The apparatus of claim 14, wherein the procedure comprises a preparation procedure for the handover of the terminal device.

24. An apparatus for wireless communication at an Integrated Access and Backhaul (IAB)) node, the apparatus comprising:

At least one processor; and

At least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:

Obtaining at least one handover label of the IAB node, the at least one handover label comprising: a third group identity indicating a third group of terminal devices to be served by the IAB node, or comprising: a fourth group identity indicating a fourth group of terminal devices not to be served by the IAB node; and

The at least one handover tag is sent to an IAB donor such that a procedure can be initiated based at least in part on the at least one handover tag, wherein the procedure is related to a handover of a terminal device of the third group of terminal devices or the fourth group of terminal devices to or from the IAB node.

25. The apparatus of claim 24, wherein the at least one handoff tag comprises a third handoff tag indicating the third group of terminal devices to be served by the IAB node, and

Wherein the third handoff tag is sent to the IAB donor such that the process can be initiated based at least in part on the third handoff tag.

26. The apparatus of claim 24, wherein the at least one handoff tag comprises a fourth handoff tag indicating that the fourth group of terminal devices will not be served by the IAB node, and

Wherein the fourth handoff tag is sent to the IAB donor such that the process can be initiated based at least in part on the fourth handoff tag.

27. An apparatus according to claim 26, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to:

A request is sent to the terminal device for reporting to the IAB donor at least one handover label for the terminal device, wherein the at least one handover label for the terminal device indicates a first group of terminal devices to be served by the IAB node or a second group of terminal devices not to be served by the IAB node.

28. An apparatus according to claim 26, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to:

Receiving at least one handover tag for the terminal device from the terminal device, wherein the at least one handover tag for the terminal device indicates a first group of terminal devices to be served by the IAB node or a second group of terminal devices not to be served by the IAB node; and

Forwarding the at least one handover label for the terminal device to the IAB donor.

29. The apparatus of claim 24, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus to send the at least one handoff tag to the IAB donor by:

The at least one handoff tag is sent to the IAB donor when the IAB node is connected to the IAB donor.

30. The apparatus of any of claims 24-29, wherein the at least one handover tag of the IAB node further comprises at least one of:

A third type indicator indicating whether the third group of terminal devices indicated by the first group identification are to be served by the IAB node; or alternatively

A fourth type indicator indicating whether the fourth group of terminal devices indicated by the second group identity is to be served by the IAB node.

31. The apparatus of claim 29, wherein the at least one handoff tag of the IAB node further comprises:

Identification of the cell; and/or

An expiration time of the at least one handoff tag.

32. A method for wireless communication, the method comprising:

Obtaining at least one handover tag for a terminal device, the at least one handover tag comprising: a first group identity indicating a first group of terminal devices to be served by an Integrated Access and Backhaul (IAB) node, or comprising: a second group identity indicating a second group of terminal devices not to be served by the IAB node; and

The method further includes transmitting the at least one handover tag to at least one base station such that a procedure related to a handover of the terminal device to or from the IAB node can be initiated by the at least one base station based at least in part on the at least one handover tag.

33. A method for wireless communication at a base station, the method comprising:

Receiving at least one handoff tag of a first Integrated Access and Backhaul (IAB) node, the at least one handoff tag comprising: a third group identity indicating a third group of terminal devices to be served by the first IAB node, or comprising: a fourth group identity indicating a fourth group of terminal devices not to be served by the first IAB node;

Receiving at least one handover tag for a terminal device, the at least one handover tag comprising: a first group identity indicating a first group of terminal devices to be handed over to served by a second IAB node, or comprising: a second group identity indicating a second group of terminal devices not to be served by a second IAB node;

Matching the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device; and

A procedure related to a handover of the terminal device to or from the first IAB node is initiated based at least in part on a match of the at least one handover tag of the first IAB node with the at least one handover tag for the terminal device.

34. A method for wireless communication at an Integrated Access and Backhaul (IAB) node, the method comprising:

Obtaining at least one handover label of the IAB node, the at least one handover label comprising: a third group identity indicating a third group of terminal devices to be served by the IAB node, or comprising: a fourth group identity indicating a fourth group of terminal devices not to be served by the IAB node; and

The at least one handover tag is sent to an IAB donor such that a procedure can be initiated based at least in part on the at least one handover tag, wherein the procedure is related to a handover of a terminal device of the third group of terminal devices or the fourth group of terminal devices to or from the IAB node.

35. A computer readable storage medium having stored therein computer executable program code instructions which, when executed by a processor, cause the processor to perform the steps of the method according to claim 32.

36. A computer readable storage medium having stored therein computer executable program code instructions which, when executed by a processor, cause the processor to perform the steps of the method according to claim 33.

37. A computer readable storage medium having stored therein computer executable program code instructions which, when executed by a processor, cause the processor to perform the steps of the method according to claim 34.