Related Applications

[0001] This application claims the benefit of provisional patent application serial number 63/324,884, filed March 29, 2022, the disclosure of which is hereby incorporated herein by reference in its entirety.

Technical Field

[0002] The present disclosure relates to operations of a cellular communications systems for providing mobility support for Integrated Access and Backhaul (IAB) nodes.

Background

[0003] In 5GS, Integrated Access and Backhaul (IAB) architecture is supported as specified in TS 23.501 clause 5.35. An IAB node can be connected to the 5G system via an IAB donor node first. Then UEs can connect to IAB node which provide the access to 5G system. However, there currently exist challenges with conventional approaches. In the current solutions, there is no mobility support for the IAB node (i.e., IAB node moves from one IAB donor node to another IAB donor node with UEs connected to the IAB node).

[0004] In RAN rel-17 work, some work has been done to support the IAB inter-CU topology redundancy, IAB inter-CU topology adaptation and IAB inter-CU backhaul RLF recovery as documented in draft CR R3-222919. There is still no support, though, for full mobility of an IAB node form one IAB donor node to another IAB donor node. SA2 has initiated a study for vehicle mounted relay (e.g., IAB node in a bus moves from one area covered by one IAB donor node to another area covered by another IAB donor node) based on lAB-architecture and several Key Issues are currently defined in TR 23.700-05 vO.l.O. Key Issue 3 is related to the IAB node mobility with connected UEs.

Summary

[0005] Methods and apparatus for providing mobility support for Integrated Access and Backhaul (IAB) nodes with connected User Equipments (UEs) are disclosed herein. Embodiments of a method performed by a network node implementing a target IAB donor node central unit (CU) of a telecommunications network are disclosed herein. The method comprises triggering a move of a plurality of UEs connected to an IAB node to switch to the target IA donor node CU via a source IAB donor node CU. The method further comprises triggering a path switch procedure towards a core network of the telecommunications network for all UEs of the plurality of UEs connected to the IAB node.

[0006] Embodiments of a network node implementing a target IAB donor node CU of a telecommunications network are also disclosed herein. The network node comprises a network interface, and processing circuitry associated with the network interface. The processing circuitry configured to cause the network node to trigger a move of a plurality of UEs connected to an IAB node to switch to the target IA donor node CU via a source IAB donor node CU. The processing circuitry is further configured to trigger a path switch procedure towards a core network of the telecommunications network for all UEs of the plurality of UEs connected to the IAB node.

[0007] Embodiments of a network node implementing a target IAB donor node CU of a telecommunications network are also disclosed herein. The network node is adapted to trigger a move of a plurality of UEs connected to an IAB node to switch to the target IA donor node CU via a source IAB donor node CU. The network node is further adapted to trigger a path switch procedure towards a core network of the telecommunications network for all UEs of the plurality of UEs connected to the IAB node.

[0008] Embodiments of a method performed by a network node implementing a target IAB donor node CU of a telecommunications network are also disclosed herein. The method comprises receiving, from a source IAB donor node CU via a core network (CN) of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node. The method further comprises providing, to the CN, a message comprising a new RRC configuration for an IAB mobile termination (MT) and resource information allocated for each UE of the plurality of UEs. The method also comprises triggering a move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU. The method additionally comprises triggering a towards the CN, including a list of the plurality of UEs, to inform the CN of a successfully move of the plurality of UEs. In some embodiments triggering the move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU comprises sending a Next Generation Application Protocol (NGAP) message to the CN to request Radio Resource Control (RRC) reconfiguration of the plurality of UEs, the NGAP message comprising RRC reconfiguration information for each UE of the plurality of UEs. Some embodiments may provide that triggering the move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU comprises sending a message via the CN to the source IAB donor node CU to trigger the move of the plurality of UEs.

[0009] Embodiments of a network node implementing a target IAB donor node CU of a telecommunications network are also disclosed herein. The network node comprises a network interface, and processing circuitry associated with the network interface. The processing circuitry is configured to cause the network node to receive, from a source IAB donor node CU via a CN of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node. The processing circuitry is further configured to provide, to the CN, a message comprising a new RRC configuration for an IAB MT and resource information allocated for each UE of the plurality of UEs. The processing circuitry is also configured to trigger a move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU. The processing circuitry is additionally configured to trigger a handover-notify message towards the CN, including a list of the plurality of UEs, to inform the CN of a successful move of the plurality of UEs. In some embodiments, the processing circuitry is further configured to cause the network node to perform any of the operations attributed to the network node above.

[0010] Embodiments of a network node implementing a target IAB donor node CU of a telecommunications network are also disclosed herein. The network node is adapted to receive, from a source IAB donor node CU via a CN of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node. The network node is further adapted to provide, to the CN, a message comprising a new RRC configuration for an IAB MT and resource information allocated for each UE of the plurality of UEs. The network node is also adapted to trigger a move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU. The network node is additionally adapted to trigger a handover-notify message towards the CN, including a list of the plurality of UEs, to inform the CN of a successful move of the plurality of UEs. In some embodiments, the network node is further adapted to perform any of the operations attributed to the network node above.

[0011] Embodiments of a method performed by a network node of a CN of a telecommunications network are also disclosed herein. The method comprises receiving, from a source IAB donor node CU, a message comprising a list of information for a plurality of UEs connected to the IAB node. The method further comprises preparing for handover for an IAB MT and all UEs of the plurality of UEs. The method also comprises sending, to a target IAB donor node CU, a message comprising resource information for the plurality of UEs connected to the IAB node. Some embodiments may provide that the method further comprises receiving, from the target IAB donor node CU, an NGAP message to request Radio Resource Configuration (RRC) reconfiguration of the plurality of UEs, the NGAP message comprising RRC reconfiguration information for each UE of the plurality of UEs, and sending the NGAP message to the source IAB donor node CU. According to some embodiments, the method may further comprise receiving, from the target IAB donor node CU, an NGAP message to request the source IAB donor node CU to trigger the mobility of the plurality of UEs connected to the IAB node, and sending the NGAP message to the source IAB donor node CU to request the source IAB donor CU to trigger the mobility of the plurality of UEs connected to the IAB node. In some embodiments, the method may further comprise sending an NGAP UE-CONTEXT-RELEASE-COMMAND message to the source IAB donor node CU, the message including a list of the plurality of UEs.

[0012] Embodiments of a network node of a CN of a telecommunications network are also disclosed herein. The network node com comprises a network interface, and processing circuitry associated with the network interface. The processing circuitry is configured to cause the network node to receive, from a source IAB donor node CU a message comprising a list of information for a plurality of UEs connected to the IAB node. The processing circuitry is further configured to cause the network node to prepare for handover for an IAB MT and all UEs of the plurality of UEs. The processing circuitry is also configured to cause the network node to send, to a target IAB donor node CU, a message comprising resource information for the plurality of UEs connected to the IAB node. In some embodiments, the processing circuitry is further configured to cause the network node to perform any of the operations attributed to the network node above.

[0013] Embodiments of a network node of a CN of a telecommunications network are also disclosed herein. The network node is adapted to receive, from a source IAB donor node CU a message comprising a list of information for a plurality of UEs connected to the IAB node. The network node is further adapted to prepare for handover for an IAB MT and all UEs of the plurality of UEs. The network node is also adapted to send, to a target IAB donor node CU, a message comprising resource information for the plurality of UEs connected to the IAB node. In some embodiments, the network node is further adapted to perform any of the operations attributed to the network node above.

[0014] Embodiments of a method performed by a network node implementing a source IAB donor node CU of a telecommunications network are also disclosed. The method comprises sending, to a target IAB donor node CU via a CN of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node. The method further comprises receiving a message via the CN from the target IAB donor node CU to trigger a move of the plurality of UEs.

Brief Description of the Drawings

[0015] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0016] Figure 1 illustrates one example of a cellular communications system in which some embodiments of the present disclosure may be implemented;

[0017] Figure 2 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point/interface according to some embodiments of the present disclosure;

[0018] Figure 3 illustrates a 5G network architecture using service-based interfaces between NFs in a control plane (CP) (instead of the point-to-point reference points/interfaces used in the 5G network architecture of Figure 2) according to some embodiments of the present disclosure; [0019] Figure 4 illustrates mobility of an Integrated Access and Backhaul (IAB) node together with connected User Equipments (UEs) according to some embodiments of the present disclosure;

[0020] Figures 5A-5B show an example of an IAB node move from an old IAB donor node to a new IAB donor node according to some embodiments of the present disclosure;

[0021] Figures 6A-6C shows another example of an IAB node move from an old IAB donor node to a new IAB donor node according to some embodiments of the present disclosure;

[0022] Figure 7 is a schematic block diagram of a radio access node according to some embodiments of the present disclosure;

[0023] Figure 8 is a schematic block diagram that illustrates a virtualized embodiment of the radio access node of Figure 7 according to some embodiments of the present disclosure;

[0024] Figure 9 is a schematic block diagram of the radio access node of Figure 7 according to some other embodiments of the present disclosure;

[0025] Figure 10 is a schematic block diagram of a wireless communication device according to some embodiments of the present disclosure; and

[0026] Figure 11 is a schematic block diagram of the wireless communication device of Figure 10 according to some other embodiments of the present disclosure.

Detailed Description

[0027] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0028] Aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. According to some embodiments disclosed herein, to enable the mobility of the Integrated Access and Backhaul (IAB) node, two parts of the IAB node, IAB-MT and IAB-DU, are moved separately first. All User Equipments (UEs) connected to the IAB node are moved as well. The move of the UEs connected to the IAB node are handled as a group. In this manner, aspects disclosed herein provide a solution to support the IAB node mobility together with the UEs connected to the IAB node.

[0029] Embodiments disclosed herein may provide one or more of the following technical advantage(s). In particular, such embodiments provide mobility with service continuity for connected UEs during IAB node mobility. In addition, group UE handling provides efficient mobility handling.

[0030] Before discussing embodiments providing mobility support for IAB nodes with connected UEs in greater detail, the following terms are first defined:

[0031] Radio Node: As used herein, a "radio node" is either a radio access node or a wireless communication device.

[0032] Radio Access Node: As used herein, a "radio access node" or "radio network node" or "radio access network node" is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.

[0033] Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

[0034] Communication Device: As used herein, a "communication device" is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehiclemounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection.

[0035] Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (loT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection.

[0036] Network Node: As used herein, a "network node" is any node that is either part of the RAN or the core network of a cellular communications network/system.

[0037] Transmission/Reception Point (TRP): In some embodiments, a TRP may be either a network node, a radio head, a spatial relation, or a Transmission Configuration Indicator (TCI) state. A TRP may be represented by a spatial relation or a TCI state in some embodiments. In some embodiments, a TRP may be using multiple TCI states. In some embodiments, a TRP may a part of the gNB transmitting and receiving radio signals to/from UE according to physical layer properties and parameters inherent to that element. In some embodiments, in Multiple TRP (multi-TRP) operation, a serving cell can schedule UE from two TRPs, providing better Physical Downlink Shared Channel (PDSCH) coverage, reliability and/or data rates. There are two different operation modes for multi-TRP: single Downlink Control Information (DCI) and multi- DCI. For both modes, control of uplink and downlink operation is done by both physical layer and Medium Access Control (MAC). In single-DCI mode, UE is scheduled by the same DCI for both TRPs and in multi-DCI mode, UE is scheduled by independent DCIs from each TRP.

[0038] In some embodiments, a set Transmission Points (TPs) is a set of geographically co-located transmit antennas (e.g., an antenna array (with one or more antenna elements)) for one cell, part of one cell or one Positioning Reference Signal (PRS) -only TP. TPs can include base station (eNB) antennas, Remote Radio Heads (RRHs), a remote antenna of a base station, an antenna of a PRS-only TP, etc. One cell can be formed by one or multiple TPs. For a homogeneous deployment, each TP may correspond to one cell.

[0039] In some embodiments, a set of TRPs is a set of geographically co-located antennas (e.g., an antenna array (with one or more antenna elements)) supporting TP and/or Reception Point (RP) functionality.

[0040] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0041] Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0042] Figure 1 illustrates one example of a cellular communications system 100 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 100 is a 5G system (5GS) including a Next Generation RAN (NG-RAN) and a 5G Core (5GC). In this example, the RAN includes base stations 102-1 and 102-2, which in the 5GS include NR base stations (gNBs) and optionally next generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), controlling corresponding (macro) cells 104-1 and 104-2. The base stations 102-1 and 102-2 are generally referred to herein collectively as base stations 102 and individually as base station 102. Likewise, the (macro) cells 104-1 and 104-2 are generally referred to herein collectively as (macro) cells 104 and individually as (macro) cell 104. The RAN may also include a number of low power nodes 106-1 through 106-4 controlling corresponding small cells 108-1 through 108-4. The low power nodes 106-1 through 106-4 can be small base stations (such as pico or femto base stations) or RRHs, or the like. Notably, while not illustrated, one or more of the small cells 108-1 through 108-4 may alternatively be provided by the base stations 102. The low power nodes 106-1 through 106-4 are generally referred to herein collectively as low power nodes 106 and individually as low power node 106. Likewise, the small cells 108-1 through 108-4 are generally referred to herein collectively as small cells 108 and individually as small cell 108. The cellular communications system 100 also includes a core network 110, which in the 5G System (5GS) is referred to as the 5GC. The base stations 102 (and optionally the low power nodes 106) are connected to the core network 110.

[0043] The base stations 102 and the low power nodes 106 provide service to wireless communication devices 112-1 through 112-5 in the corresponding cells 104 and 108. The wireless communication devices 112-1 through 112-5 are generally referred to herein collectively as wireless communication devices 112 and individually as wireless communication device 112. In the following description, the wireless communication devices 112 are oftentimes UEs, but the present disclosure is not limited thereto.

[0044] Figure 2 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point/interface. Figure 2 can be viewed as one particular implementation of the system 100 of Figure 1. [0045] Seen from the access side the 5G network architecture shown in Figure 2 comprises a plurality of UEs 112 connected to either a RAN 102 or an Access Network (AN) as well as an AMF 200. Typically, the R(AN) 102 comprises base stations, e.g., such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in Figure 2 include a NSSF 202, an AUSF 204, a UDM 206, the AMF 200, a SMF 208, a PCF 210, and an Application Function (AF) 212.

[0046] Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE 112 and AMF 200. The reference points for connecting between the AN 102 and AMF 200 and between the AN 102 and UPF 214 are defined as N2 and N3, respectively. There is a reference point, Nil, between the AMF 200 and SMF 208, which implies that the SMF 208 is at least partly controlled by the AMF 200. N4 is used by the SMF 208 and UPF 214 so that the UPF 214 can be set using the control signal generated by the SMF 208, and the UPF 214 can report its state to the SMF 208. N9 is the reference point for the connection between different UPFs 214, and N14 is the reference point connecting between different AMFs 200, respectively. N15 and N7 are defined since the PCF 210 applies policy to the AMF 200 and SMF 208, respectively. N12 is required for the AMF 200 to perform authentication of the UE 112. N8 and N10 are defined because the subscription data of the UE 112 is required for the AMF 200 and SMF 208.

[0047] The 5GC network aims at separating UP and CP. The UP carries user traffic while the CP carries signaling in the network. In Figure 2, the UPF 214 is in the UP and all other NFs, i.e., the AMF 200, SMF 208, PCF 210, AF 212, NSSF 202, AUSF 204, and UDM 206, are in the CP. Separating the UP and CP guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from CP functions in a distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and data network for some applications requiring low latency.

[0048] The core 5G network architecture is composed of modularized functions. For example, the AMF 200 and SMF 208 are independent functions in the CP. Separated AMF 200 and SMF 208 allow independent evolution and scaling. Other CP functions like the PCF 210 and AUSF 204 can be separated as shown in Figure 2. Modularized function design enables the 5GC network to support various services flexibly.

[0049] Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the CP, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The UP supports interactions such as forwarding operations between different UPFs.

[0050] Figure 3 illustrates a 5G network architecture using service-based interfaces between the NFs in the CP, instead of the point-to-point reference points/interfaces used in the 5G network architecture of Figure 2. However, the NFs described above with reference to Figure 2 correspond to the NFs shown in Figure 3. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. In Figure 3 the service based interfaces are indicated by the letter "N" followed by the name of the NF, e.g., Namf for the service based interface of the AMF 200 and Nsmf for the service based interface of the SMF 208, etc. The NEF 300 and the NRF 302 in Figure 3 are not shown in Figure 2 discussed above. However, it should be clarified that all NFs depicted in Figure 2 can interact with the NEF 300 and the NRF 302 of Figure 3 as necessary, though not explicitly indicated in Figure 2.

[0051] Some properties of the NFs shown in Figures 2 and 3 may be described in the following manner. The AMF 200 provides UE-based authentication, authorization, mobility management, etc. A UE 112 even using multiple access technologies is basically connected to a single AMF 200 because the AMF 200 is independent of the access technologies. The SMF 208 is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF 214 for data transfer. If a UE 112 has multiple sessions, different SMFs 208 may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF 212 provides information on the packet flow to the PCF 210 responsible for policy control in order to support QoS. Based on the information, the PCF 210 determines policies about mobility and session management to make the AMF 200 and SMF 208 operate properly. The AUSF 204 supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM 206 stores subscription data of the UE 112. The Data Network (DN), not part of the 5GC network, provides Internet access or operator services and similar.

[0052] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

[0053] Aspects disclosed herein for providing mobility support for IAB nodes with connected UEs are now discussed in greater detail. Solutions discussed herein address for support IAB node mobility between inter-IAB-donor-CU together with the UEs connected to the IAB node. In particular, the solutions discussed herein address both mobility of the IAB-MT (e.g., during inter-IAB-donor-CU) as well as mobility of the UEs connected to the IAB-DU.

[0054] Exemplary operations for IAB node mobility with change of IAB donor node via Xn are first discussed. In RAN Rel-17 IAB work, the inter-IAB-donor-CU change of IAB-MT is supported due to topology adaptation for a single-connected IAB node. The IAB-MT switches connection from an old path (e.g., via the old IAB donor node) to a new path (e.g., via new IAB donor node), while the IAB DU part of the IAB remains under the control of the old IAB donor node. Support is also provided for the switch of the IAB-DU part from the old IAB donor node to the new IAB donor node. In addition, the UE connects to the IAB node also switches from the old path to the new path via the new IAB donor node.

[0055] Figure 4 illustrates the mobility of an IAB node together with connected UEs according to some examples disclosed herein.

[0056] Figures 5A-5B show an example of the IAB node moves from old IAB donor node to the new IAB donor node (i.e., IAB node mobility for inter lAB-donor-CU with Xn interface). At step 500, the source lAB-donor-CU triggers the move of IAB-MT from south path to target path as specified in TS 38.401 for Rel-17. At step 502, the target lAB-donor-CU send NGAP Path Switch Request to AMF for the IAB-MT. At step 504, the operations in clause 4.9.1.2.2/4.9.1.2.3 between AMF/SMF/UPF(s) are performed. [0057] At step 506, the AMF sends the NGAP Path Switch Request Acknowledge message to target lAB-donor-CU. At step 508, the target lAB-donor-CU trigger the UE context release towards the source lAB-donor-CU which in turn triggers furth release of resource on the source path related to IAB-MT. At step 510, the Fl-C connection between migration IAB node and target lAB-donor-CU is established based on new TNL addresses information exchanged in step 500. The target lAB-donor-CU configures BH RLC channels, BAP-sublayer routing entries and mapping rules on the target path. Note that the details of path and configuration management depend on the work in RAN WGs. At step 512, the target lAB-donor-CU triggers the move of the group of UEs connected to IAB node to switch to the target lAB-donor-CU via the source lAB-donor- CU. Note that the details of the move of UEs connected to IAB node depend on the work in RAN WGs. Operations then continue at step 514 in Figure 5B.

[0058] Referring now to Figure 5B, at step 514, when UE connects to the target lAB- donor-CU via RRC signalling, the target lAB-donor-CU triggers the path switch procedure towards the 5GC for all the UEs connected to IAB node. At step 516, the steps in clause 4.9.1.2.2/4.9.1.2.3 between AMF/SMF/UPF(s) are performed. It is to be understood that, in circumstances in which the UEs served by a mobile node are served by different AMFs (e.g., different AMFs within a set of AMFs, or even different AMFs from different sets of AMFs), the path switch operations are performed by these multiple old AMFs and new AMFs for the corresponding group of UEs. At step 518, the AMF sends the NGAP Path Switch Request Acknowledge message to target lAB-donor- CU. Finally at step 520, the target lAB-donor-CU triggers the UE context release towards the source lAB-donor-CU which in turn triggers furth release of resource on the source path related to IAB-MT.

[0059] In case of IAB node mobility between IAB donor node without Xn interface, the move of the IAB-MT and the UEs connect to the IAB node can be performed via 5GC using N2 interface. In this regard, Figures 6A-6C shows an example of the IAB node moves from old IAB donor node to the new IAB donor node (i.e., IAB node mobility for inter lAB-donor-CU with N2 interface). In Figure 6A, at step 600, the source lAB-donor-CU sends a HANDOVER REQUIRED message to the target lAB-donor- CU over the N2 interface. This message may also include a list of information for the UEs connected to the IAB node. This message includes the request of migrating IAB node's TNL address information in the RRC container. At step 602, the ON prepare the handover for IAB-MT and all connected UEs as specified in step 2-8 of clause 4.9.1.3.2 in TS 23.502. At step 604, the ON sends the HANDOVER REQUEST message to target lAB-donor-CU, including the transparent container from source lAB-donor-CU and the resource information prepared in CN for all the UEs. At step 606, the target lAB-donor- CU performs admission control, allocates resources for lAB-MT/UEs connected to the IAB node involving target lAB-donor-DU. Note that the detailed handling of UEs connected to IAB node depends on the work in RAN WGs.

[0060] At step 608, the target lAB-donor-CU provides the new RRC configuration for the IAB-MT as part of the HANDOVER REQUEST ACKNOWLEDGE message. The RRC configuration includes a BAP address of the lAB-donor-DU in the target lAB-donor-CU's topology, default BH RLC channel and a default BAP routing ID configuration for UL Fl- C/non-Fl traffic mapping on the target path. The RRC configuration may include the new TNL address(es) anchored at the target lAB-donor-DU for the migrating node as requested in step 1. The target lAB-donor-CU also provides the resource information allocated for all connected UEs. At step 610, the CN performs steps 11-12 of clause 4.9.1.3.2 in TS 23.502 for IAB-MT and all connected UEs. At step 612, the CN sends the HANDOVER COMMAND to source lAB-donor-CU including the RRC configuration information received in step 5. [0061] At step 614, the source lAB-donor-CU performs steps 2-3 of clause 4.9.1.3.3 of 23.502 for IAB-MT of the migrating IAB node. The IAB-MT of the migrating IAB node performs step 4 of clause 4.9.1.3.3 towards the target lAB-donor-CU. At step 616, the target lAB-donor-CU triggers the NGAP HANDOVER NOTIFY message towards the 5GC for the migrating IAB-MT. At step 618, the ON and the IAB-MT of the IAB node perform steps 6-12 of clause 4.9.1.3.3 in TS 23.502 for the IAB-MT. At step 620, the ON triggers NGAP UE CONTEXT RELEASE COMMAND message towards the source lAB- donor-CU which in turn triggers furth release of resource on the source path related to IAB-MT. Operations then continue at step 622 of Figure 6B.

[0062] Turning now to Figure 6B, at step 622, the Fl-C connection between migration IAB node and target lAB-donor-CU is established based on new TNL addresses information for IAB node exchanged in step 5. The target lAB-donor-CU configures BH RLC channels, BAP-sublayer routing entries and mapping rules on the target path. At step 624, the target lAB-donor-CU triggers the move of the group of UEs connected to IAB node to switch to the target lAB-donor-CU via CN and source lAB-donor-CU. One alternative for step 624 is based on the handlings in step 600-608 above that the resources for the all UEs connected to the IAB node are prepared at the target path. The target lAB-donor-CU performs further the following:

[0063] At step 624a.1: The target lAB-donor-CU sends a NGAP message, e.g., Connected UE Reconfiguration Request message to CN (e.g., target AMF) to request the RRC reconfiguration of the UEs connected to the migrating IAB node. The message includes RRC Reconfiguration information for all connected UEs.

[0064] At step 624.2: If there is AMF change, the target AMF sends a message to source AMF, e.g., the Namf_COMMUNICATIN_N2infoNotify including the RRC Reconfiguration information for all connected UEs.

[0065] At step 624a.3: The CN (e.g., the source AMF) sends the NGAP message, e.g., Connected UE Reconfiguration Command message to the source lAB-donor-CU including the RRC reconfiguration information.

[0066] Another alternative for step 624 is based on that there is no handling of the UEs connected to the IAB node in step 600-608 above. The target lAB-donor-CU needs to trigger the source lAB-donor-CU node to trigger the move of the UEs connected to the IAB node with separate signalling: [0067] At steps 624b.l-624b.3: The target lAB-donor-CU sends message via CN to source lAB-donor-CU to trigger the move of UEs connected to the IAB node. Example messages (e.g., NGAP messages in steps 624b.l/624b.3 and service operation between AMFs in steps 624b.2) are showing in the figure. These messages may not be linked to a particular UE.

[0068] At steps 624b.4-624.11: After receiving the request from target lAB-donor-CU above, the source lAB-donor-CU performs the steps as specified in clause 4.9.1.2.2/3 in TS 23.502 with following enhancement: the NGAP messages between RAN and CN, and the service operations between AMFs (e.g., steps 624b.4 1 624b.5 I 624b.7 1 624b.9 1 624b.11) includes the list of UEs connected to the IAB node. The message may link to one of the UE that connected to the IAB node or it's not linked to a specific UE.

[0069] The source lAB-donor-CU, via migrating IAB node, sends the RRCReconfiguration message to each connected UE based on one of the two alternatives discussed above. It is to be understood that, in circumstances in which the UEs served by a mobile node are served by different AMFs (e.g., different AMFs within a set of AMFs, or even different AMFs from different sets of AMFs), the group signalling described above between the RAN and the CN is performed towards these multiple old AMFs and new AMFs for the corresponding group of UEs. Operations then resume at step 626 in Figure 6C.

[0070] Referring now to Figure 6C, at step 626, the UEs connect to the migrating IAB node perform step 4 of clause 4.9.1.3.3 towards the target lAB-donor-CU as a response to the RRC reconfiguration in step 624. At step 628, the target lAB-donor-CU triggers the HANDOVER NOTIFY message towards 5GC including the list of UEs connected to the IAB node. At step 630, the CN performs steps 6-11 of clause 4.9.1.3.3 in TS.23.502 for all connected UEs. Finally, at step 632, the CN sends NGAP UE CONTEXT RELEASE COMMAND message to the source lAB-donor-CU including the list of UEs connected to the IAB node. The source lAB-donor-CU triggers the release of resource on the source path.

[0071] In some examples, the impacts on services, entities, and interfaces are as follows:

[0072] For the gNB:

[0073] - Supports the inclusion of UEs connected to IAB node.

[0074] For the AMF: [0075] - Supports HO with group handling.

[0076] Figure 7 is a schematic block diagram of a radio access node 700 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The radio access node 700 may be, for example, a base station 102 or 106 or a network node that implements all or part of the functionality of the base station 102 or gNB described herein. As illustrated, the radio access node 700 includes a control system 702 that includes one or more processors 704 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory 706, and a network interface 708. The one or more processors 704 are also referred to herein as processing circuitry. In addition, the radio access node 700 may include one or more radio units 710 that each includes one or more transmitters 712 and one or more receivers 714 coupled to one or more antennas 716. The radio units 710 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 710 is external to the control system 702 and connected to the control system 702 via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) 710 and potentially the antenna(s) 716 are integrated together with the control system 702. The one or more processors 704 operate to provide one or more functions of a radio access node 700 as described herein. In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 706 and executed by the one or more processors 704.

[0077] Figure 8 is a schematic block diagram that illustrates a virtualized embodiment of the radio access node 700 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. Again, optional features are represented by dashed boxes.

[0078] As used herein, a "virtualized" radio access node is an implementation of the radio access node 700 in which at least a portion of the functionality of the radio access node 700 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node 700 may include the control system 702 and/or the one or more radio units 710, as described above. The control system 702 may be connected to the radio unit(s) 710 via, for example, an optical cable or the like. The radio access node 700 includes one or more processing nodes 800 coupled to or included as part of a network(s) 802. If present, the control system 702 or the radio unit(s) are connected to the processing node(s) 800 via the network 802. Each processing node 800 includes one or more processors 804 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 806, and a network interface 808.

[0079] In this example, functions 810 of the radio access node 700 described herein are implemented at the one or more processing nodes 800 or distributed across the one or more processing nodes 800 and the control system 702 and/or the radio unit(s) 710 in any desired manner. In some particular embodiments, some or all of the functions 810 of the radio access node 700 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 800. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 800 and the control system 702 is used in order to carry out at least some of the desired functions 810. Notably, in some embodiments, the control system 702 may not be included, in which case the radio unit(s) 710 communicate directly with the processing node(s) 800 via an appropriate network interface(s).

[0080] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of radio access node 700 or a node (e.g., a processing node 800) implementing one or more of the functions 810 of the radio access node 700 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0081] Figure 9 is a schematic block diagram of the radio access node 700 according to some other embodiments of the present disclosure. The radio access node 700 includes one or more modules 900, each of which is implemented in software. The module(s) 900 provide the functionality of the radio access node 700 described herein. This discussion is equally applicable to the processing node 800 of Figure 8 where the modules 900 may be implemented at one of the processing nodes 800 or distributed across multiple processing nodes 800 and/or distributed across the processing node(s) 800 and the control system 702.

[0082] Figure 10 is a schematic block diagram of a wireless communication device 1000 according to some embodiments of the present disclosure. As illustrated, the wireless communication device 1000 includes one or more processors 1002 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 1004, and one or more transceivers 1006 each including one or more transmitters 1008 and one or more receivers 1010 coupled to one or more antennas 1012. The transceiver(s) 1006 includes radio-front end circuitry connected to the antenna(s) 1012 that is configured to condition signals communicated between the antenna(s) 1012 and the processor(s) 1002, as will be appreciated by on of ordinary skill in the art. The processors 1002 are also referred to herein as processing circuitry. The transceivers 1006 are also referred to herein as radio circuitry. In some embodiments, the functionality of the wireless communication device 1000 described above may be fully or partially implemented in software that is, e.g., stored in the memory 1004 and executed by the processor(s) 1002. Note that the wireless communication device 1000 may include additional components not illustrated in Figure 10 such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device 1000 and/or allowing output of information from the wireless communication device 1000), a power supply (e.g., a battery and associated power circuitry), etc.

[0083] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device 1000 according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0084] Figure 11 is a schematic block diagram of the wireless communication device 1000 according to some other embodiments of the present disclosure. The wireless communication device 1000 includes one or more modules 1100, each of which is implemented in software. The module(s) 1100 provide the functionality of the wireless communication device 1000 described herein.

[0085] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

[0086] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

[0087] Some exemplary embodiments of the present disclosure are as follows: [0088] Embodiment 1: A method performed by a network node implementing a target Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the method comprising:

• triggering (512) a move of a plurality of User Equipments (UEs) connected to an IAB node to switch to the target IAB donor node CU via a source IAB donor node CU; and

• triggering (514) a path switch procedure towards a core network of the telecommunications network for all UEs of the plurality of UEs connected to the IAB node. [0089] Embodiment 2: A network node (700) implementing a target Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the network node comprising:

• a network interface (706); and

• processing circuitry (702) associated with the network interface, the processing circuitry configured to cause the network node to: o trigger (512) a move of a plurality of User Equipments (UEs) connected to an IAB node to switch to the target IAB donor node CU via a source IAB donor node CU; and o trigger (514) a path switch procedure towards a core network of the telecommunications network for all UEs of the plurality of UEs connected to the IAB node.

[0090] Embodiment 3: A network node (700) implementing a target Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the network node adapted to:

• trigger (512) a move of a plurality of User Equipments (UEs) connected to an IAB node to switch to the target IAB donor node CU via a source IAB donor node CU; and

• trigger (514) a path switch procedure towards a core network of the telecommunications network for all UEs of the plurality of UEs connected to the IAB node.

[0091] Embodiment 4: A method performed by a network node implementing a target Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the method comprising:

• receiving (604), from a source IAB donor node CU via a core network (CN) of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node;

• providing (604), to the CN, a message comprising a new RRC configuration for an IAB mobile termination (MT) and resource information allocated for each UE of the plurality of UEs;

• triggering (624) a move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU; and • triggering (628) a message towards the CN, including a list of the plurality of UEs, to inform the CN of a successful move of the plurality of UEs.

[0092] Embodiment 5: The method of embodiment 4, wherein triggering (624) the move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU comprises sending (624a.1) a Next Generation Application Protocol (NGAP) message to the CN to request Radio Resource Control (RRC) reconfiguration of the plurality of UEs, the NGAP message comprising RRC reconfiguration information for each UE of the plurality of UEs.

[0093] Embodiment 6: The method of any one of embodiments 4-5, wherein triggering the move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU comprises sending (624b.l-624b.3) a message via the CN to the source IAB donor node CU to trigger the move of the plurality of UEs.

[0094] Embodiment 7: A network node (700) implementing a target Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the network node comprising:

• a network interface (706); and

• processing circuitry (702) associated with the network interface, the processing circuitry configured to cause the network node to: o receive (604), from a source IAB donor node CU via a core network (CN) of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node; o provide (604), to the CN, a message comprising a new RRC configuration for an IAB mobile termination (MT) and resource information allocated for each UE of the plurality of UEs; o trigger (624) a move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU; and o trigger (628) a message towards the CN, including a list of the plurality of UEs, to inform the CN of a successful move of the plurality of UEs.

[0095] Embodiment 8: The network node of embodiment 7, wherein the processing circuitry is further configured to cause the network node to perform the method of any one of claims 5 and 6. [0096] Embodiment 9: A network node (700) implementing a target Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the network node adapted to:

• receive (604), from a source IAB donor node CU via a core network (CN) of the telecommunications network, a message comprising resource information for a plurality of UEs connected to the IAB node;

• provide (604), to the CN, a message comprising a new RRC configuration for an IAB mobile termination (MT) and resource information allocated for each UE of the plurality of UEs;

• trigger (624) a move of the plurality of UEs to switch to the target IAB donor node CU via the CN and the source IAB donor node CU; and

• trigger (628) a message towards the CN, including a list of the plurality of UEs, to inform the CN of a successful move of the plurality of UEs.

[0097] Embodiment 10: The network node of embodiment 9, wherein the network node is further adapted to perform the method of any one of claims 5 and 6.

[0098] Embodiment 11: A method performed by a network node of a core network (CN) of a telecommunications network, the method comprising:

• receiving (600), from a source Integrated Access and Backhaul (IAB) donor node central unit (CU) a message comprising a list of information for a plurality of User Equipments (UEs) connected to the IAB node;

• preparing (602) for handover for an IAB mobile termination (MT) and all UEs of the plurality of UEs; and

• sending (604), to a target IAB donor node CU, a message comprising resource information for the plurality of UEs connected to the IAB node.

[0099] Embodiment 12: The method of embodiment 11, further comprising:

• receiving (624a.1), from the target IAB donor node CU, a Next Generation Application Protocol (NGAP) message to request Radio Resource Configuration (RRC) reconfiguration of the plurality of UEs, the NGAP message comprising RRC reconfiguration information for each UE of the plurality of UEs; and

• sending (624a.3) the NGAP message to the source IAB donor node CU.

[0100] Embodiment 13: The method of any one of embodiments 11-12, further comprising: • receiving (624b.1), from the target IAB donor node CU, a Next Generation Application Protocol (NGAP) message to request the source IAB donor node CU to trigger the mobility of the plurality of UEs connected to the IAB node; and

• sending (624b.3) the NGAP message to the source IAB donor node CU to request the source IAB donor CU to trigger the mobility of the plurality of UEs connected to the IAB node.

[0101] Embodiment 14: The method of any one of embodiments 11-13, further comprising sending (632) an NGAP U E-CONTEXT-RELEASE-COMMAND message to the source IAB donor node CU, the message including a list of the plurality of UEs.

[0102] Embodiment 15: A network node (700) of a core network (CN) of a telecommunications network, the network node comprising:

• a network interface (706); and

• processing circuitry (702) associated with the network interface, the processing circuitry configured to cause the network node to: o receive (600), from a source Integrated Access and Backhaul (IAB) donor node central unit (CU) a message comprising a list of information for a plurality of User Equipments (UEs) connected to the IAB node; o prepare (602) for handover for an IAB mobile termination (MT) and all UEs of the plurality of UEs; and o send (604), to a target IAB donor node CU, a message comprising resource information for the plurality of UEs connected to the IAB node.

[0103] Embodiment 16: The network node of embodiment 15, wherein the processing circuitry is further configured to cause the network node to perform the method of any one of claims 12-14.

[0104] Embodiment 17: A network node (700) of a core network (CN) of a telecommunications network, the network node adapted to:

• receive (600), from a source Integrated Access and Backhaul (IAB) donor node central unit (CU) a message comprising a list of information for a plurality of User Equipments (UEs) connected to the IAB node;

• prepare (602) for handover for an IAB mobile termination (MT) and all UEs of the plurality of UEs; and

• send (604), to a target IAB donor node CU, a message comprising resource information for the plurality of UEs connected to the IAB node. [0105] Embodiment 18: The network node of embodiment 16, wherein the network node is further adapted to perform the method of any one of claims 12-14.

[0106] Embodiment 19: A method performed by a network node implementing a source Integrated Access and Backhaul (IAB) donor node central unit (CU) of a telecommunications network, the method comprising:

• sending (604), to a target IAB donor node CU via a core network (CN) of the telecommunications network, a message comprising resource information for a plurality of User Equipments (UEs) connected to the IAB node; and

• receiving (624b.l-624b.3) a message via the CN from the target IAB donor node CU to trigger a move of the plurality of UEs.

[0107] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.