Managing wireless backhaul link status in a wireless network

Abstract

Methods for use in managing link status of a wireless backhaul link in a wireless network including a WAB node are disclosed. The WAB node includes a MT component and a gNB component. The method at a

Description

FIELD OF THE INVENTION The present invention generally relates to methods for use in managing or providing the wireless backhaul link status in a wireless network or wireless communication system. For example, the disclosure relates to methods for use in a process for managing notification of the wireless backhaul link status in a wireless communication system involving at least one Wireless Access Backhaul, WAB, node. BACKGROUND Wireless communication systems are largely deployed to address a wide range of applications, from mobile broadband, massive machine type communications to Ultra Reliable Low Latency Communications (URLLC). Such systems allow a plurality of user equipment (UE) or mobile terminals to share the wireless medium to exchange several types of data content (e.g. video, voice, messaging ...) over a radio access network (RAN) through one or more base stations (gNBs). The base stations are conventionally wired-connected (e.g. through fiber) to a core network, forming an intermediate network, named backhaul (BH). Examples of such wireless multiple-access communication systems include systems based on 3rd generation partnership project (3GPP - RTM) standards, such as fourth-generation (4G) Long Term Evolution (LTE) or recent fifth-generation (5G) New Radio (NR) systems, or systems-based IEEE 802.11 standards, such as WiFi. The demand for network densification increases due to the rising number of users and higher throughput requirement. Facing the issues of high deployment costs and time of the wired backhaul networks with network densification, 3GPP has proposed, from release 16 for 5G NR, a wireless backhaul, also known as Integrated Access and Backhaul, IAB, where part of the wireless (i.e. radio) spectrum is used for the backhaul connection of base stations instead of fiber. The wireless backhaul communications (between base stations) may use the same radio resources as access communications (between a base station and UEs). IAB turns out to be a competitive alternative to the fiber-based backhauling in dense areas or areas difficult to cover, as it allows scalable and rapid installations without the burden of cabling the base stations. IAB is most likely to operate in the millimeter wave (mmWave) band to achieve the required Gbps (gigabits per second) data rate. Urban environments are usually characterised by a high density of users along with the presence of a significant number of vehicles (e.g. public / private passengers transportation, goods delivery, food trucks ...). The speed of some of the vehicles may be pretty low or at least similar to pedestrian speed and some of these vehicles may even be temporarily stationary. Some of these vehicles (e.g. buses, trains or trams), may have predictable routes and / or limited mobility areas (e.g. some vehicles, such as food trucks or promotional vehicles, may be located outside stadiums or show venues) while others may have predictable stationary locations (e.g. taxis). 3GPP is considering that such vehicles could offer an opportunity to increase network coverage and connectivity to the UEs inside the vehicles, or even to UEs in proximity to the vehicles, by installing on these vehicles on-board base stations (or base station elements) that would act as relays. These relays would rely on 5G wireless backhaul (typically IAB, or Integrated Access &Backhaul) for connecting to a fixed donor device. Thus, based upon the fixed IAB foundations set out in Releases 16 and 17, 3GPP is now considering mobile IAB systems and architecture, as a part of the Release 18 framework, in order to address scenarios focusing on mobile lAB-nodes mounted on vehicles (for example, a bus, a train, a taxi). In such scenarios, mobile lAB-nodes can also be referred to as Vehicle Mounted Relays (VMR), providing 5G coverage / capacity to on-board and / or surrounding UEs. The technical benefits of using vehicle relays include, among others, the ability of the relay vehicle to get better coverage than the nearby UE, thanks to better RF / antenna capabilities, thus providing the UE with a better link to the macro network. Additionally, a vehicle relay is expected to have less stringent power / battery constraints than the UEs. Some enhancements further considered by 3GPP for Release 19, consider the need for 5G access for UEs onboard aircrafts, cruise ships, helicopters and vehicles in remote areas with limited sky visibility (e.g. where terrestrial cellular coverage or Wi-Fi coverage is not available), support for onboard / on-site mobile edge computing (MEC), local services, and direct local inter-UE communications, or local gNB deployment in public safety or disaster recovery scenarios. The backhauling links for the base stations providing the 5G access in such scenarios would then be operated over either a terrestrial network (TN), or a non-terrestrial network (NTN), with a possibility to handover communications from a terrestrial network to a non-terrestrial network and vice-versa. Such base stations can be referred to as Wireless Access Backhaul (WAB) nodes, or mobile WAB nodes, or WAB nodes. As part of these wireless backhauling enhancements, 3GPP is also considering some evolution to the former LTE-based Femto framework, including a new 5G Femto or 5G Femtocell that would offer 5G indoor coverage improvement while allowing high bandwidth and throughput at home for new immersive applications such as AR / VR / MR gaming, e-sports, UHD 8K video, telepresence, etc. It can be noted that a WAB node may deploy 5G Femto cells to serve UEs inside vehicles. WAB nodes serving UEs use backhaul links to exchange data (in the user plane and the control plane) and these backhaul links are wireless in the context of WAB networks. It means that the protocol messages in the control plane exchanged between the base station of a WAB node and the core network (NG protocol), and between the base station of a WAB node and other base stations of the Radio Access Network (Xn protocol), are transmitted through a wireless link. Actually, NG and Xn protocols are designed for wired networks, meaning that these protocols assumed that the medium used for the transmission of messages is reliable, and so, when applied to communication through wireless links, these protocols are not resilient to degradation of the wireless link quality. As a consequence, some NG and Xn procedures may fail in the context of WAB networks because of poor radio conditions for the wireless backhaul link. This situation may lead to system failure and interruption of service at the UEs served by a WAB node. When a problem is detected on a wireless backhaul link, some actions may be taken in the WAB node, in the base station serving the WAB node, and / or in the core network. For instance, the priority may be given to control plane data transmission to prevent from system failure. The wireless backhaul link status can be assessed at the device on both side of the wireless backhaul link, i.e. at the WAB node itself or at the base station serving the WAB node. However, the backhaul link status cannot be assessed at a core network function and at other base stations of the Radio Access Network (RAN). There is therefore a need to improve the management of problems on the wireless backhaul link in wireless networks including a WAB node. SUMMARY In accordance with an aspect of the invention, there is provided a method for use in managing link status of a wireless backhaul link in a wireless network including a Wireless Access Backhaul, WAB, node, the WAB node including a mobile termination, MT, component and a gNB component, the method at a network entity associated with the WAB node including: sending information for indicating a link status of a wireless backhaul link supporting one or more Radio Access Network, RAN, interfaces associated with the WAB node. In accordance with another aspect of the invention, there is provided a method for use in managing link status of a wireless backhaul link in a wireless network including a Wireless Access Backhaul, WAB, node, the WAB node including a mobile termination, MT, component and a gNB component, the method at a network entity associated with a WAB node including: receiving information for indicating a link status of a wireless backhaul link supporting one or more Radio Access Network, RAN, interfaces associated with the WAB node. In accordance with another aspect of the present invention, there is provided an apparatus for a network entity as recited in claim 48 of the accompanying claims. By providing information indicating the status of the wireless backhaul link to one or more other network entities, such as one or more AMF entities and / or one or more NG-RAN nodes (which may include a backhaul RAN node serving the WAB node), core network entities (e.g. the UE AMF(s) and / or the BH AMF) and / or base station(s) of a Radio Access Network (RAN) can be informed about a wireless backhaul link status when a WAB node is wirelessly connected to the core network and the RAN through this wireless backhaul link and take appropriate action. The present invention therefore introduces new signaling messages to inform a core network function and / or base station(s) of a Radio Access Network (RAN) about a wireless backhaul link status when a base station (e.g. WAB node) is wirelessly connected to the core network and the RAN through this wireless backhaul link. Further example features of the invention are described in other dependent claims. Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus / device / unit aspects, and vice versa. Furthermore, features implemented in hardware may be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly. For example, in accordance with other aspects of the invention, there are provided a computer program comprising instructions which, when the program is executed by one or more processing units, cause the one or more processing units to carry out the method of any aspect or example described above or below and a computer readable storage medium carrying the computer program. BRIEF DESCRIPTION OF THE DRAWINGS Different aspects of the invention will now be described, by way of example only, and with reference to the following drawings in which: Figure 1 is a schematic diagram of a communication system in which the present invention may be implemented according to one or more example embodiments; Figure 2 is a simplified schematic diagram of a 5G system in which the present invention may be implemented according to one or more example embodiments; Figure 3 is a simplified schematic diagram of a 5G system involving a Wireless Access Backhaul (WAB) node, and in which the present invention may be implemented according to one or more example embodiments. Figure 4 is a block schematic diagram of an example network node or base station in accordance with one or more embodiments of the invention; Figure 5 is a simplified schematic diagram showing an example of a wireless communication system, including a WAB network or WAB network system, in which embodiments and examples of embodiments of the present invention may be implemented; Figure 6a is a schematic diagram illustrating the protocol stack associated to the NG or Xn interface in the user plane (NG-U or Xn-U); Figure 6b is a schematic diagram illustrating the protocol stack associated to the NG or Xn interface in the control plane (NG-C or Xn-C); Figure 7a is a schematic diagram showing an example message flow for performing the procedure for the notification of a wireless backhaul link status from a NG-RAN node to an AMF of the core network; Figure 7b is a schematic diagram showing an example message flow for performing the procedure for the notification of a wireless backhaul link status from a UE to an AMF of the core network; Figure 8a is a schematic diagram showing an example message flow for performing the procedure for the notification of a wireless backhaul link status from a UE to a NG-RAN node; Figure 8b is a schematic diagram showing an example message flow for performing the procedure for the notification of a wireless backhaul link status from a first NG RAN node to a second NG-RAN node; Figure 9a is a schematic diagram showing an example message flow for performing the procedure for a UE to provide to a NG-RAN node a list of AMF(s) involved in a wireless backhaul link; Figure 9b is a schematic diagram showing an example message flow for performing the procedure for a first NG-RAN node to provide to a second NG-RAN node a list of AMF(s) involved in a wireless backhaul link; Figure 10 is a flowchart of an example method for managing at a UE or a NG-RAN node the notification of a backhaul link status to an AMF or a NG-RAN node; Figure 11 is a flowchart of an example method for managing at an AMF or a NG-RAN node the reception of the notification of a backhaul link status. DETAILED DESCRIPTION Figure 1 illustrates an example communication system 100 in which the present invention may be implemented according to one or more embodiments. As depicted, the example system 100 is a wireless communication system, in particular a mobile radio communication system such as a fifth-generation (5G) New Radio (NR) system including a Wireless Access Backhaul (WAB) communication system or network. Although in the following description, embodiments and examples of embodiments of the present invention will be described with respect to a 5G NR system, it will be appreciated that it is not intended that the present invention is limited to 5G NR systems and may be used in any wireless communication systems having an integrated access and backhaul communication system which shares radio resources for wireless access links and wireless backhaul links. The system 100 comprises a plurality ofUEs (User Equipment) 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154, a communication satellite 160, a satellite dish 101, a remote core network 170, three fixed Base Stations 102, 103 and 104, a plurality of Wireless Access Backhaul (WAB) nodes 110 (mounted on plane 161), 120a and 120b (mounted on train 162), 140 (mounted on Unmanned Aerial Vehicle (UAV) UAV 164) and 150 (mounted on backpack 165 or other carrier that can be carried by a user (e.g. in a disaster zone)), and a Wireless Access Backhaul node 130 (or Home gNB, mounted in house 163) which is fixed but based on the same architecture as a WAB node. In more general terms, the WAB node may be mounted on or in a vehicle (such as a train, bus, taxi, tram, etc.) and / or an aircraft or flying vehicle (such as a plane, UAV, helicopter, etc. ) and / or a building (such as a house, enterprise / company / office building, hotel building, airport building, sports / event buildings, shopping centre building, etc..) and / or a portable carrier that can be carried by a user (such as a backpack, bag, etc), for example, in a disaster zone or for public safety or for emergency services, and / or public infrastructure elements or units (such as lamp posts, traffic lights, etc.). In an example where the WAB node is implemented in a Femto network, the WAB node functions as a 5G Femto node and may be mounted at a building (such as a house, enterprise / company / office building, hotel building, airport building, sports / event buildings, shopping centre building, etc..) and / or public infrastructure elements or units (such as lamp posts, traffic lights, etc.). When it is a mobile base station, a WAB node is also referred to as a Mobile WAB (MWAB) node. Some examples ofUEs include smartphones / tablets (such as UEs 111, 123, 134, 142, 152), XR headsets (such as UEs 112, 122, 132), cameras (such as UEs 141 and 151), fixed video cameras (such as UEs 113, 121, 133, 153) or mobile / wearable video cameras (such as UEs 143 and 154). In general, the UE may be any portable or handheld or mobile telephone, a smartphone, a tablet, a portable or fixed computer, fixed or mobile camera, portable television or other similar wireless communication device. In the following description, the term UE will be used and it is not intended to limit the description to any particular type of wireless communication device. Base stations 102, 103 and 104 are interconnected through a wired link infrastructure 180, preferably based on optical fiber or any other wired means. Base stations 102, 103 and 104 are also connected to the core network 170 through a wired link infrastructure 190, preferably based on optical fiber or any other wired means. In embodiments and examples of embodiments of the invention, base stations 102, 103 and 104 are 5G NR base stations (referred to as a gNB), as defined in 3GPP TS 38.300 vl8.0.0 specification document. Satellite dish 101 (e.g. satellite gateway) is also connected to wired link infrastructure 180 or 190, or to both infrastructures. Besides infrastructures 180 and 190 may be the same infrastructure. In one example, a part of a base station is embedded in the satellite 160 while the other part is embedded in the gateway 101, meaning that the base station is split between the satellite 160 and the gateway 101. In another example, a full base station is embedded in the satellite 160 and the gateway 101 connects the base station 160 with the infrastructure 180 or 190. In case of non-geostationary satellite, the satellite 160 may connect to different gateways, like the gateway 101, while the satellite 160 is moving around the earth. In order to extend the network coverage of base stations 102,103 and 104 and reach the remote UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154, mobile WAB nodes or WAB nodes, or WAB-nodes, 110, 120a, 120b, 130, 140 and 150, have been installed on vehicles / mobile equipment 161, 162, 163, 164 and 165. By acting as relaying nodes between the base stations 102, 103 and 104 and the UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154, WAB-nodes 110, 120a, 120b, 130, 140 and 150 allow overcoming the reachability issue resulting from limited sky visibility while ensuring support for onboard / on-site mobile edge computing (MEC), local services, and direct local inter-UE communications. This allows further communication between base stations 102, 103 and 104 and the UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154 and / or communications between the UEs served by a same WAB-node (e.g., UEs 151, 152, 153 and 154 connected to WAB node 150). The base stations 102, 103 and 104, the WAB nodes 110, 120a, 120b, 130, 140 and 150, the satellite 160, the satellite dish 101 are thus forming a backhaul network or WAB network (also referred to as WAB topology), or WAB network (also referred to as WAB topology), which accommodates UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154. The terms WAB network, WAB network, WAB topology and WAB topology will be used interchangeably in the following. The WAB network is part of the Radio Access Network (RAN) or as referred to with respect to 5G, the Next Generation (NG) RAN. The base stations 102, 103 and 104, the WAB nodes 110, 120a, 120b, 130, 140 and 150, the satellite 160, the satellite dish 101, and the core network 170 are thus forming a WAB system, or WAB system, which accommodates UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154. The terms WAB system and WAB system will be used interchangeably in the following. A base station, or gNB, such as base station 102, 103 or 104, is a logical node that provides the NR-connectivity, hosting both higher layer protocols, such as PDCP (Packet Data Convergence Protocol) and RRC (Radio Resource Control) protocols, and lower layer protocols, such as the RLC (Radio Link Control), MAC (Medium Access Control) and physical layer protocols. The WAB nodes 110, 120a, 120b, 130, 140 and 150, which may serve multiple radio sectors, are wireless backhauled to the base station 102, 103 or 104, via a single logical hop associated to a single radio link (i.e., radio links D1041a, D1041b, D1031, D1022, D1021), or split into two radio links in the case of satellite relaying (radio links DI60la and DI60lb). Although a single logical hop is shown in figure 1, it will be appreciated that the WAB nodes could be wirelessly backhauled to the base station over multiple logical hops (for example, similar to the multiple hops provided in an IAB network). Each WAB node consists of or includes a gNB or RAN node or base station component or entity which is referred to as a WAB-gNB, or WAB base station, and Mobile Termination (MT) component or entity which is referred to as an IAB-MT, or WAB-Mobile Termination. The WAB-gNB functionality on an WAB-node allows or enables the WAB-node to serve UEs. The WAB-MT functionality includes, e.g., physical layer, layer-2, RRC and Non-Access Stratum (NAS) functionalities and allows or enables the WAB-MT to connect to a fixed base station, or gNB, such as base station 102, 103 or 104 and to support backhauling of traffic related to the WAB-gNB of the WAB node. The WAB-gNB may also be referred to as a NG-RAN node (of a WAB node) and the WAB-MT may also be referred to as a UE (of a WAB node). WAB nodes 110, 120a, 120b, 140 and 150 are intended to be mobile devices that will move along with the vehicle they are mounted on. However, these WAB nodes may remain at a fixed location for a significant duration when their associated vehicle is remaining still (e.g., a train may stop at a railway station, a plane may be parked at an airport for a while, a car / truck / fire engine or any other emergency vehicle may be parked nearby a disaster area). WAB node 130 is likely to remain at fixed location and may be a 5G Femto node, which provides NR access at home or at enterprise premises. In such case, the 5G Femto node 130 may have a direct connection DI700 to the Core Network 170 through the wired link infrastructure 190, which is preferably based on optical fiber or any other wired means. Figure 2 is a simplified schematic diagram of a 5G system 200 in which the present invention may be implemented according to one or more example embodiments. This figure illustrates the possible standardized interfaces between the various elements composing the system. First, it represents a User Equipment (UE) 201 having a Uu interface with the New Generation (NG) Radio Access Network (RAN or NG-RAN) 202, and a N1 interface with an Access and Mobility management Function (AMF) entity or AMF 212 in a 5G core network (5GC) 210. Each base station composing the RAN 202 has a N2 interface with one or more Access and Mobility management Function (AMF) entity or AMF, like AMF 212, and a N3 interface with one or more User Plane Function (UPF) entity or UPF, like UPF 211. The N1 interface is used to convey Non-Access Stratum (NAS) protocol messages between a UE 201 and an AMF 212. NAS messages are used for the signaling between the UE and the core network for various procedures such as registration, session establishment, security, and mobility management. Actually, NAS messages are conveyed through the Uu interface between the UE 201 and the RAN 202, and the N2 interface between the RAN 202 and the AMF 212. An AMF 212 is responsible for handling registration, authentication, connection and mobility management tasks for a UE. For a WAB node, the AMF may apply the procedures defined in NAS protocol specifications (TS 24.502 section 5), considering the WAB node is a Mobile Base Station Relay (MBSR) introduced in Release 18. There may be several AMFs in a 5G core network, a standardized interface N14 enables the communications between AMFs. When a UE registers to the network through a serving base station, the serving base station will connect to an AMF suitable to handle the UE. When the UE 201 is registered, one or more Protocol Data Unit (PDU) session(s) can be set up to transfer data flows between the UE 201 and the Data Network (DN) 220 providing internet access. A PDU session is established between a UE 201 and a User Plane Function (UPF) 211 in the 5G core network 210. In the user plane, the UPF 211 connects to the Data Network (DN) 220 through the interface N6, and it is responsible for data packets routing with the required Quality of Service (QoS). There may be several UPFs on the data path with a N9 interface between UPFs. The user data between a UE 201 and the Data Network 220 are thus conveyed through interfaces Uu, N3, N6 and potentially N9. In the control plane, the setup of PDU sessions is handled through NAS messages involving the Session Management Function (SMF) entity or SMF 213 in the 5G core network 210. The NAS messages are still exchanged between the UE 201 and the AMF 212 through the N1 interface, but an additional interface N11 between an AMF 212 and the SMF 213 is used to reach the SMF 213. In a 5G core network, the SMF is responsible for the setup, modification, and release of PDU sessions for a UE, as well as the Internet Protocol (IP) address allocation for the UE. To manage a PDU session, the SMF 213 controls the UPF 211 (configuration) based on QoS policy defined for the PDU session. For this purpose, a N4 interface exists between the SMF 213 and the UPF 211. A base station in RAN 202 operating in a first Public Land Mobile Network (PLMN) may serve a UE having a subscription for a second PLMN (called home PLMN) different from the first PLMN (called visited PLMN). In such a roaming case, there are two options to provide the UE 201 with an access to the Data Network 220. In a first option called home routed, the UPF and its controlling SMF to access the Data Network 220 are located in the 5G core network for the home PLMN. However, the SMF of the visited PLMN controls the intermediate UPF(s) of the visited PLMN, and interacts with the SMF of the home PLMN. In a second option called local breakout, the UPF and its controlling SMF to access the Data Network 220 are located in the 5G core network for the visited PLMN. However, the SMF interacts with the home 5G core network to get QoS policies associated with the UE’s PDU session(s). Nl, N2, N3, N4, N6, N9, Nil, N14 may also be called reference points as defined in TS 23.501. Figure 3 is a simplified schematic diagram of a 5G system 300 involving a Wireless Access Backhaul (WAB) node (or a MW AB node), and in which the present invention may be implemented according to one or more example embodiments. This figure first represents a User Equipment (UE) 301 served by a WAB node 310 through the Uu interface. The WAB node 310 is composed of or includes a MT or WAB-MT or MWAB-MT unit / component / entity 311 (also called WAB-UE), and a gNB or WAB-gNB, or MWAB-gNB unit / component / entity 312. Through the WAB-gNB 312, a WAB node acts as a gNB for UEs providing access to the 5G network, i.e. providing a NR access link to the UEs that can be located inside or outside the entity, such as a vehicle, equipped with the WAB node 310 (e.g. on entering / leaving the vehicle). In other words, the WAB-gNB 312 includes full base station or gNB function (including both Central Unit (CU) and distributed unit (DU)) and MT function, where the gNB function is used to communicate with UEs for access service and the MT function is used to communicate with another gNB for backhauling purpose. The WAB node 310 wirelessly connects to the 5G Core Network (using NR Uu interface) through an IP connectivity provided by PDU session(s) established by the WAB-MT 311 via a gNB 320, which can be called a backhaul RAN node, BH RAN node, backhaul base station, backhaul gNB or BH gNB. Acting as a legacy UE, the WAB-MT 311 connects via a NG-RAN cell of the BH gNB 320, through a backhaul link (e.g. a wireless backhaul link) that may be a direct link or via a satellite (e.g. when the WAB node 310 is embedded in an airplane). Thus, a PDU session is provided either by a Terrestrial Network (TN) or by a Non-Terrestrial Network (NTN). In addition, the WAB node 310 may embed some core network functions, like a UPF 313, to enable local services to the served UEs. The traffic associated to these local services does not need to use the links to / from the core network via the BH gNB 320, which has the advantages to reduce the load on these links and to run applications having very low latency requirements. For example, where the WAB node 310 includes a UPF 313, the WAB node can connect to one or more local servers (e.g. mounted at the same entity as the WAB 310) enabling a UE served by the WAB access to local services provided by the local servers with no traffic required outside of the WAB node / server environment. The BH gNB 320 provides N3 and N2 interfaces so that the WAB-MT 311 can access the functions of its 5G core network 330 (or backhaul 5GC or BH 5GC). Indeed, a WAB-MT 311 may have access to some or several PLMNs through the appropriate subscriptions, and it may connect in a non-roaming manner to one PLMN, e.g. PLMN1 supported by the BH gNB 320, and may then have access to the corresponding 5G core network 330. In particular the WAB-MT 311 interacts with the AMF 332, which can be called the WAB AMF or backhaul AMF or BH AMF, and establishes PDU session(s) with the UPF 331, which can be called the WAB UPF or backhaul UPF or BH UPF. The WAB UPF 331 is controlled by the SMF 333 (through N4 interface), which can be called the WAB SMF or backhaul SMF of BH SMF, and which also interacts with the WAB AMF 332 (through N11 interface). There may be one or several intermediate UPFs between the BH gNB 320 and the WAB UPF 331 as mentioned in the Figure 2. An interface internal to the WAB node 310 exists between the WAB-gNB 312 and the WAB-MT 311, which may be implemented on different or the same hardware resources. For instance, these two functions are implemented on the same processing unit 402 of Figure 4, and interactions exist between the two functions. Once the WAB-MT 311 has established a PDU session with the WAB UPF 331, the WAB node is ready to serve UEs and the WAB-gNB 312 can start operating as a legacy gNB. The WAB-gNB may support various PLMNs and the UE 301 connects to one PLMN, e.g. PLMN2, which may be different from the PLMN 1 the WAB-MT 311 connects to. In the case where PLMN 1 and PLMN2 are different, the UE 301 connects to the 5G core network 340 (or UE 5GC), including a UPF 341, which can be called the UE UPF, an AMF 342, which can be called the UE AMF, and a SMF 343, which can be called the UE SMF. The UE SMF 343 interacts with the UE AMF 342 (through N11 interface) and the UE UPF 341 (through N4 interface). In the case where the PLMN1 and the PLMN2 are the same, the UE UPF 341, the UE AMF 342, the UE SMF 343, the WAB UPF 331, the WAB AMF 332, and the WAB SMF 333 belong to the same 5G core network 350. In addition, the UE UPF 341 and the WAB UPF 331 may be the same UPF, the UE AMF 342 and the WAB AMF 332 may be the same AMF, the UE SMF 343 and the WAB SMF 333 may be the same SMF. The connections between the UE 301 to the UE UPF 341 and to the UE AMF 342 are possible thanks to the N6 interface between the UE UPF 341 and the WAB UPF 331, and thanks to the N6 interface between the WAB UPF 331 and the UE AMF 342. These N6 interfaces enable the establishment of N2 interface between the WAB-gNB 312 and the UE AMF 342, and the establishment of N3 interface between the WAB-gNB 312 and the UE UPF 341, which allows the UE 301 to access the Data Network 360. In case the WAB-MT 311 connects to the 5G network in a roaming manner corresponding to the home routed option, then the PLMN1 is the visited PLMN and the WAB UPF 331 connects to another UPF not represented in the Figure 3 in the home PLMN through a N9 interface. It is this other UPF that provides the connection to the UE UPF 341 and the UE AMF 342 through N6 interfaces. In case the WAB-MT 311 connects to the 5G network in a roaming manner corresponding to the local breakout option, then the PLMN1 is the visited PLMN and the WAB UPF 331 directly connects to the UE UPF 341 and the UE AMF 342 through N6 interfaces as shown in the Figure 3. Figure 4 is a block schematic diagram of an example network node or RAN node or base station 400, such as base stations or gNBs or WAB nodes shown in Figure 1, in accordance with one or more embodiments of the invention. Each of a WAB node 110, 120a, 120b, 130, 140, or 150 of figure 1 may comprise the elements of the base station of figure 4. Also, the satellite 160 of figure 1 may comprise the elements of the base station of figure 4. In the following description, the network node 400 will be referred to generally as a base station. As will be apparent to a skilled person, Figure 4 is a simplified schematic diagram and shows only some of the functional components of an example base station 400 for use in describing the one or more embodiments of the invention. The base station 400 includes components for transmitting and receiving communications. As shown in Figure 4, the base station 400 includes a processing unit 402, a wireless interface 404, one or more antennas 410, a network interface 432, and memory 418. The network interface 432 manages communications of the base station 400 with the core network, other base stations, local network functions (like UPF), or local servers. It may provide a standardized interface, wired (e.g. fiber) or wireless, to support these communications. Through this network interface 432, the base station 400 may implement the standardized interfaces N2 (based on NGAP protocol) and N3 (based on GPRS tunneling protocol) with the core network, and the standardized interface Xn (based on XnAP protocol) with other base station of the Radio Access Network (RAN), all defined by the 3GPP standard. The network interface 432 may not be present or active in case the base station 400 is a WAB node that does not support local services, that is not used as a legacy base station like base station 102, 104 in Figure 1, and that is not used as a home base station providing Femto cells like base station 130 in Figure 1. The wireless interface 404 is configured to provide wireless communication via communication links (414) with other wireless devices, such as one or more UEs, e.g. link D1041b between base station 104 and the MT / UE unit of WAB node 120b, or link D1202 between the gNB unit of WAB node 120b and the UE 122. In case of WAB node, the wireless interface 404 may then be used both for the wireless backhaul link(s) with backhaul base station(s) and for the wireless link(s) with the UE(s) served by the WAB node. The wireless interface 404 may be compliant with a fifth-generation (5G) New Radio (NR) system and thus implementing the Uu interface defined by 3GPP standard, or with other wireless communication system. The wireless interface 404 is coupled to the processing unit 402 and to one or more antennas (such as the antenna 410). The wireless interface 404 typically includes a receiving unit 406 and a transmitting unit 408. The configuration of the wireless interface 404 may be limited to connect to one antenna, but preferably several antennas are used, in order to provide beamforming capability. Although not shown in Figure 4, the receiving unit 406 typically includes elements such as a receiver, demodulator, decoder, and the transmitting unit 408 typically includes elements such as a transmitter, modulator, coder. The receiving unit 406 and transmitting unit 408 may together be referred to as a transceiver. The processing unit 402 is configured to carrying out processing for operation of the base station 400. The processing unit 402 may be a single processor (e.g. Central Processing Unit) or may comprise two or more processors. The number of processors and the allocation of processing functions to the processors is a matter of design choice for a skilled person. The base station 400 includes memory 418 for storing data and computer programs containing instructions for the operation of the base station 400. Memory 418 includes RAM (Random Access Memory), ROM (Read Only Memory), or combination of both or as a non-limiting example a mass storage device such as a disk or a Solid-State Drive. Memory 418 includes a program memory in which are stored programs containing processor instructions for operation of the base station 400 and for implementing the methods in accordance with one or more embodiments of the invention. The programs may contain a number of different program elements or sub-routines (represented by element 420 in memory 418) containing processor instructions for a variety of different tasks, for example, for determining the status of a communication link (radio conditions, congestion...), sending notification or information indicating a link status of a wireless communication link to another device (e.g. a wireless backhaul link) and / or indicating a status change of the communication link to a remote device, applying action to take into account the status or a status change of the communication link. Memory 418 may further include memory (e.g. RAM) for storing information such as, communication link status (e.g. information indicating link status of a wireless backhaul link as discussed below), a list of identifiers of remote devices. For example, information stored in memory 418 may include one or more identifiers of Access and Mobility Function entities such as the BH AMF ID and UE AMF ID List as discussed below, identifiers of different network nodes as discussed below, such as the identifiers of the backhaul RAN node serving a WAB node (e.g. in the case where the network node is the WAB node), identifiers of the MT component and gNB component of a WAB node. The operation of the program elements or sub-routines 420 will be described in more detail below. In an example arrangement, a communication bus 424 provides communication and interoperability between the various elements included in the base station 400 or connected to it. The representation of the bus is not limiting and in particular, the processing unit 402 is operable to communicate instructions to any element of the base station 400 directly or by means of another element of the base station 400. In an example implementation, the base station 400 may be or may include an apparatus comprising one or more processing units or processors for performing or implementing the methods in accordance with one or more embodiments of the invention. In other words, the apparatus is capable of performing one or more functions of the base station including performing the methods in accordance with one or more embodiments of the invention by means of the one or more processing units. For example, the one or more processing units uses software to implement the one or more embodiments of the invention as described above with reference to the processing unit 402 of Figure 4. Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, a CPU of a microcontroller Unit (MCU), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated (e.g. on an Integrated Circuit) or discrete logic circuitry. However, alternatively, the one or more processing units for performing or implementing the methods may be implemented in hardware: for example, in the form of an Application Specific Integrated Circuit or ASIC or other hardware comprising logic element (s). Accordingly, the term “processing unit” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In a 5G core network, an AMF (Access and Mobility management Function) like the WAB AMF 332 or the UE AMF 342, may be implemented with the apparatus described in the Figure 4 where the Wireless Interface 404 and the antenna 410 is not present. Figure 5 illustrates an example of a wireless communication system 500, including a WAB network or WAB network system, in which embodiments and examples of embodiments of the present invention may be implemented. A WAB network will also be referred to as a WAB network system, WAB topology, WAB system, topology or system and so in this application, the terms WAB network system, WAB network, WAB topology, WAB system, topology or system will be used interchangeably. The WAB network system of Figure 5, is composed of three base stations 501, 502 and 503, also referred to as Backhaul base stations, or backhaul RAN nodes (also referred to as BH RAN nodes), or backhaul gNBs (also referred to as BH-gNB), two core networks 510 and 520, with the respective AMF entities 511a and 511b (for Core Network 510) and 521a and 521b (for Core Network 520) and the respective UPF entities 512a and 512b (for Core Network 510) and 522a and 522b (for Core Network 520), and two WAB nodes 530 and 540. A wired backhaul IP network 590 interconnects the base stations 501, 502 and 503 and the Core Networks 510 and 520. For instance, this wired link consists of optical fiber cable(s). As discussed above, each WAB node comprises a Mobile Termination (MT) component or part or unit (WAB-MT 531 for WAB node 530 and WAB-MT 541 for WAB node 540) and a RAN node or base station or gNB component or part or unit (WAB-gNB 532 for WAB node 530 and WAB-gNB 542 for WAB node 540). WAB node 530 and WAB node 540 may also embed a UPF entity, respectively UPF entity 533 and UPF 543, as previously discussed in figure 3, allowing WAB-node 530 to provide UEs 551, 552 and 561 with some local services, such as for instance inter-UE communication where the user data exchanged between the two UEs would be routed through UPF entity 533 / 543 instead of being routed through a UPF entity belonging to Core Network 510 or 520. WAB node 530 is connected to the serving backhaul base station referred to as BH-gNBl, 501 through the wireless backhaul (BH) link 5011. WAB node 540 may be connected to the serving backhaul base station referred to as BH-gNB2, 502 through the wireless backhaul (BH) link 5021 or to the serving backhaul base station referred to as BH-gNB3, 503 through wireless backhaul (BH) link 5031 or, in case of dual connectivity, to both the serving backhaul base station BH-gNB2, 502 through BH link 5021 and the serving backhaul base station BH-gNB3, 503 through BH link 5031. WAB-gNB 532 of WAB node 530 is also connected to UE 551 through communication link or radio link 5301 and to UE 552 through communication link or radio link 5302. Similarly, WAB-gNB 542 of WAB node 540 is also connected to UE 561 through communication link or radio link 5401. Although Figure 5 shows only UE 561 connected to WAB node 540, it will be appreciated that there will be a plurality of UEs connected to WAB nodes of the wireless communication system. WAB-gNB 532 and WAB-MT 531 may be connected to a same AMF function or entity (e.g., AMF 511a) or to different AMF functions or entities belonging to the same Core Network (e.g., AMF 511a and AMF 51 lb) or to different Core Network (e.g., AMF 511a and AMF 521a). Some AMF functions may be implementing WAB-specific features for managing a WAB node (e.g., advanced mobility features). Some AMF functions may not implement such features but may still be capable of serving a WAB node with a limited set of basic features. Some AMF functions may not be capable of serving a WAB node. The processes and arrangements for managing one or more network connections and managing WAB node authorization in a wireless communication system including one or more WAB nodes will now be described according to some embodiments of the present invention. Several scenarios are possible according to the mobility of WAB nodes 530 and 540. As a first scenario, and taking the example of WAB node 540, a dual-connectivity configuration may be applied to the WAB-MT 541, initially connected to BH-gNB2 502 only through the link 5021. Indeed, the WAB-MT 541 periodically performs a cell search procedure, as defined in 3GPP TS 38.300, trying to detect PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal). The WAB-node may report to BH-gNB2 502 the presence of a new cell, for instance one cell managed by the BH-gNB3 503, through a measurement report. Based on the analysis of the measurement report, the BH-gNB2 502 may request to the BH-gNB3 503 the establishment of a dual connectivity for the WAB-MT 541 with an additional connection through the link 5031. The BH-gNB3 503 may accept the request and proceed to the connection of the WAB-MT 541 according to the procedure described in TS 37.340 section 10.2.2. As a result, the WAB-MT 541, and thus the WAB node 540 is dual-connected. The BH-gNB2 502 may take benefit of the dual connectivity of WAB node 540 to balance the traffic load by offloading some traffic (data / user traffic or control traffic) initially planned to be transmitted through the link 5021. Some or all the traffic associated to the WAB node 540 (i.e. control data related to the WAB node, and control and user data related to the UEs served by the WAB node 540) may be transmitted through the link 5031 and through the IP connectivity between BH-gNB2 502 and BH-gNB3 503. Dual-connectivity configuration is however transparent for the MWAB-gNB 542 and for the UEs served by the WAB-gNB 542. As a second scenario, the radio link 5021 may experience radio link deficiency due to some unexpected interference or shadowing phenomena. For such reasons, the WAB-MT 541 may lose the connection with the BH-gNB2 502 and declare a Radio Link Failure (RLF). Then, the WAB- MT 541 will try to reestablish the connection in the same or a different cell controlled by BH gNB2 502 or by another gNB. Thus, the WAB-MT 541 may try to connect to a cell controlled by BH-gNB3 503 by requesting the establishment of the link 5031. In this case, the reestablishment procedure described in TS 38.300 section 9.2.3.3 may be applied, which enables a UE to maintain the RRC connection. With such procedure, the BH gNB3 503 sends to the BH gNB2 502 a request to retrieve the context of the WAB-MT 541. Based on the response from the BH gNB2 502, the BH gNB3 503 may accept the connection of the WAB-MT 541. Then, all the traffic related to the WAB node 540 (and the served UEs) will now transit through the BH gNB 503. The reestablishment procedure does not involve the WAB-gNB 542 and its served UEs. If the reestablishment is rapidly performed after RLF, the service interruption at the UE 561 may be avoided or limited. As a third scenario, the WAB-MT 541 may be handed over from the current serving cell to a new cell. Indeed, based on the measurement reports provided by the WAB-MT 541, the BH-gNB2 502 may detect that the WAB-MT 541 would have a better connection through a cell managed by the BH gNB3 503. Then, the BH-gNB2 502 may trigger a handover procedure described in TS 38.300 section 9.2.3.2. In this procedure, the BH-gNB2 502 sends a handover request to the BH gNB3 503 along with information related to the WAB-MT 541. Based on this information, the BH gNB3 503 may accept the handover request and proceed to the admission of the WAB-MT 541. Then, all the traffic related to the WAB node 540 (and the served UEs) will now transit through the BH gNB 503. The handover procedure does not involve the WAB-gNB 542 and its served UEs, and it may be transparent for WAB-gNB and the served UEs (no interruption of service). The three situations described above may happen because the backhaul link 5021 between the WAB-MT 541 and the BH gNB2 502 is wireless and subject to degradation, not only because the WAB-node 540 may be mobile, but also because the radio conditions may be changing leading to poor link budget. Moreover, in case of high throughput demand from applications running in UEs served by a WAB node (e.g. UEs 551 and 552 served by the WAB-gNB 532), the wireless backhaul link between the WAB node and the serving backhaul RAN node (e.g. link 5011 between WAB-MT 531 and BH-gNB 501) may be congested even if the radio quality is very good. When the quality of a wireless link is degraded, there may be no solution of handover at that time. Taking the example of the WAB node 530, if the quality of the wireless backhaul link 5011 decreases (because of congestion or bad radio conditions), it may not be possible to handover the WAB-MT 531 to another cell, as the WAB-MT 531 may not be located in a place covered by another cell. In case of quality degradation of a communications link, some messages transmitted through this link may be delayed or lost. This situation may alter the user applications, but also the procedures to manage the system in the user plane. In particular for a WAB system, a NG or Xn procedure may fail due to the quality degradation of the wireless backhaul link supporting the transmission of NG and Xn protocol messages. In such a situation, the network devices or entities which are part of the wireless network and which generate and / or schedule traffic on the wireless backhaul link may reduce the amount of data to be transmitted and / or prioritize the transmission of critical data. In WAB system, these network devices are the gNB component of the WAB node (i.e. the WAB-gNB), the backhaul RAN node(s) serving the WAB node, the NG-RAN nodes having a Xn connection with the WAB-gNB, and the AMF(s) having a NG connection with the WAB-gNB. Taking the example of figure 5 and the wireless backhaul link 5011, these network devices include the WAB-gNB 532, the BH-gNBl 501, and may include the AMFs 51 la, 51 lb, 521a, 521b, BH-gNB2 502, BH-gNB3 503. The network devices at each side of the wireless backhaul link are able to detect a change on the link quality (degradation or improvement). For instance, the assessment of the wireless backhaul link may be performed according to the measured Reference Signal Receive Power (RSRP) and / or, Reference Signal Receive Quality (RSRQ), or according to the average number of retransmission necessary at MAC layer or RLC layer to transmit packets. Besides, the congestion of the link may be detected through the monitoring of the transmission buffers. Considering the wireless backhaul link 5011, the network devices able to assess the quality of the link (e.g. radio quality and / or congestion of this link) are the WAB node 530 (e.g. the WAB-MT 531) and the BH-gNBl 501. In uplink (i.e. for transmissions from the WAB-MT 531 to the BH-gNBl 501), a congestion or load can be detected by the WAB-MT 531, while in downlink (i.e. for transmissions from the BH-gNBl 501 to the WAB-MT 531) the congestion or load can be detected by the BH-gNBl 501). The WAB-MT or MT component of the WAB node may inform the BH RAN node serving the WAB node about uplink congestion (e.g. as described with reference to figure 8a) and the BH RAN node may inform the WAB-MT or MT component of the WAB node of downlink congestion (e.g. as described with reference to figure 8a), or inform the WAB-gNB or gNB component of the WAB node of downlink congestion (e.g. as described with reference to figure 8b). The other network devices, such as the AMF entities in the core network or RAN nodes neighbouring the WAB node 530 may not be able to detect any change on the status of the wireless backhaul link 5011. In order to inform these other devices about the status of the wireless backhaul link, methods in accordance with one or more embodiments of the invention can be used and examples of such methods are described below with the help of figures 7a, 7b, 8a, 8b, 9a, 9b, 10 and 11. For instance, a status of the wireless backhaul link 5011 may be provided (e.g. in a notification): - to an AMF like the AMF 51 la by the WAB-gNB 532 through the procedure described at the figure 7a (the WAB-gNB 532 being previously informed by the WAB-MT 531 through the interface internal to the WAB node 530), to an AMF like the AMF 51 la by the WAB-MT 532 through the procedure described at the figure 7b, - to the backhaul NG-RAN node serving the WAB node 530 (i.e. BH-gNBl 501) by the WAB-MT 531 through the procedure described at the figure 8a, to a NG-RAN node in the neighbourhood or vicinity of the WAB node 530 (e.g. BH-gNB2 502) by the WAB-gNB 532 through the procedure described at the figure 8b (the WAB-gNB 532 being previously informed by the WAB-MT 531 through the interface internal to the WAB node 530), to a NG-RAN node in the neighbourhood or vicinity of the WAB node 530 (e.g. BH-gNB2 502) by the backhaul NG-RAN node serving the WAB node 530 (i.e. BH-gNBl 501) through the procedure described at the figure 8b, to an AMF like the AMF 511a by the backhaul NG-RAN node serving the WAB node 530 (i.e. BH-gNBl 501) through the procedure described at the figure 7a. For this latter case, and when the AMF 511a is a UE’s AMF handling UEs served by WAB-gNB 532, the BH-gNB 1501 has to know that a NG connection is established between the AMF 511a and the WAB-gNB 532. Thus, information or AMF information identifying one or more AMF entities associated with or connected to or interacting with (e.g. having an active NG connection with) the WAB-gNB 532 of the WAB node 530 may be provided to the backhaul NG-RAN node (501). The information, such as a list of AMFs having an active NG connection with the WAB-gNB 532 (e.g. a list of ID(s) for the UE AMF(s)), may be provided to the BH-gNB 1 501: o by the WAB-MT 531 through the procedure described at the figure 9a, the WAB-MT 531 being previously informed of the information (e.g. list of AMFs) by the WAB-gNB 532 through the interface internal to the WAB node 530, o by the WAB-gNB 532 through the procedure described at the figure 9b. It can be noted that the AMF 511a may be a UE’s AMF(s) handling UEs served by WAB-gNB 532, or the AMF 511a may be the backhaul AMF (or BH AMF) handling the WAB-MT 531. Thus, information or AMF information identifying one or more AMF entities associated with a WAB node (the one or more AMF entities may be the WAB or BH AMF entity and / or one or more UE AMF entities) may be provided (e.g. to the BH RAN node serving the WAB node) by the MT component of the WAB node (e.g. as described with reference to figure 9a) or by the gNB component of the WAB node (e.g. as described with reference to figure 9b). An advantage of using the backhaul NG-RAN node serving a WAB node 530 (i.e. BH-gNBl 501) to inform an AMF is that the notification message does not need to be transmitted over the wireless backhaul link that may be degraded, which reduces the risk of delay or loss of the notification. Figure 6a is a schematic diagram 600 illustrating the protocol stack associated to the NG or Xn interface in the user plane, referred to as NG-U or Xn-U. The NG-U interface and the associated Transport Network Layer (TNL) protocol stack are described in the following 3GPP specifications: TS 38.410, TS 38.411, TS 38.414. The Xn-U interface and the associated TNL protocol stack are described in the following 3GPP specifications: TS 38.420, TS 38.421, TS 38.424. The NG user plane interface (NG-U) is defined between a NG-RAN node and a UPF. The Xn user plane interface (Xn-U) is defined between two NG-RAN nodes. Both interfaces are built on IP (Internet Protocol) transport. GTP-U (GPRS (General Packet Radio Service) Tunnelling Protocol for User Plane) 601 is used on top of UDP (User Datagram Protocol) 602 and IP 603 to carry the user plane PDUs between the NG-RAN node and the UPF (for NG-U), or user plane PDUs between two NG-RAN nodes (for Xn-U). GTP-U 601 is defined in TS 29.281, while UDP 602 is defined in IETF RFC 768, and IP 603 is defined in IETF RFC 8200 (for IPv6) and IETF RFC 791 (for IPv4). Any data link layer 604 and physical layer 605 that fulfil the requirements toward the upper layers 601, 602, 603 may be used. For instance, they can be implemented with Ethernet protocol over fiber cables. Figure 6b is a schematic diagram 610 illustrating the protocol stack associated to the NG or Xn interface in the control plane, referred to as NG-C or Xn-C. The NG-C interface and the associated Transport Network Layer (TNL) protocol stack are described in the following 3GPP specifications: TS 38.410, TS 38.411, TS 38.412, TS 38.413. The Xn-C interface and the associated TNL protocol stack are described in the following 3GPP specifications: TS 38.420, TS 38.421, TS 38.422, TS 38.423. The NG control plane interface (NG-C) is defined between a NG-RAN node and an AMF. The Xn control plane interface (Xn-C) is defined between two NG-RAN nodes. Both interfaces are built on IP (Internet Protocol) transport. NGAP (Next Generation Application Protocol) 611 is used on top of SCTP (Stream Control Transmission Protocol) 612 and IP 613 to carry the control plane data between the NG-RAN node and the AMF (for NG-C), or between two NG-RAN nodes (for Xn-C). NGAP 611 is defined in TS 38.413, XnAP 611 is defined in TS 38.423, while SCTP 612 is defined in IETF RFC 4960, IP 603 is defined in IETF RFC 8200 (for IPv6) and IETF RFC 791 (for IPv4). Any data link layer 614 and physical layer 615 that fulfil the requirements toward the upper layers 611, 612, 613 may be used. For instance, they can be implemented with Ethernet protocol over fiber cables. Several NGAP elementary procedures to manage aNG-C interface are specified in TS 38.413. First a NG setup procedure (described in TS 38.413 section 8.7.1) enables the establishment of a NG interface between a NG-RAN node (like WAB-gNB 542) and an AMF (like AMF 521a). This procedure shall be the first NGAP procedure triggered after the TNL association (TNLA) has become operational. For this purpose, the NG-RAN node and the AMF need to determine their IP addresses, through for instance, DNS (Domain Name System) resolution. This first TNL association shall be reserved for the NGAP elementary procedures that utilize non-UE associated signalling (i.e for generic procedures not associated to a UE). The AMF Configuration Update procedure (described in TS 38.413 section 8.7.3) enables an AMF to provide updated configuration data to the NG-RAN node. In particular, the AMF may use it to establish additional TNL association(s) between the NG-RAN node and the AMF, or to release additional TNLA(s). Indeed, configurations with multiple SCTP endpoints per NG-RAN node / AMF pair should be supported. When configurations with multiple SCTP associations are supported, the AMF may request to dynamically add / remove SCTP associations between the NG-RAN node / AMF pair. Within the set of SCTP associations established between one AMF and NG-RAN node pair, the AMF may request the NG-RAN node to restrict the usage of SCTP association for certain types of NG-C signalling. The RAN Configuration Update procedure (described in TS 38.413 section 8.7.2) enables a NG-RAN node to provide updated configuration data to the AMF. In particular, the AMF may use it to request the release of additional TNLA(s) between the NG-RAN node and the AMF. Error Indication, AMF Status Indication, Overload Start, Overload Stop are procedures descripted in TS 38.413 respectively in sections 8.7.5, 8.7.6, 8.7.7 and 8.7.9. They allow an AMF to report information related to the current conditions of the NG interface between a NG-RAN node and the AMF. NG Reset procedure (described in TS 38.413 section 8.7.4) can be initiated either by a NG-RAN node or by an AMF to initialise or re-initialise a NG-C interface between a NG-RAN node and an AMF. In addition, to the above non-UE associated procedures, the UE TNLA Binding Release procedure (described in TS 38.413 section 8.13.1) enables an AMF to request an NG-RAN to release existing NGAP UE TNLA binding(s). A UE TNLA binding is the association of a UE served by the NG-RAN node and connected to the AMF, with an existing TNL association between the AMF and the NG-RAN node. It means that every NAS message exchanged between the UE and the AMF will be conveyed through a NGAP message between the NG-RAN node and the AMF using the selected TNLA. This NGAP UE TNLA binding is performed at the registration of the UE to the AMF as described in TS 23.502 section 4.2.7.2. Referring now also to figure 7a which is a schematic diagram showing an example message flow 700 for performing a procedure for the notification of a wireless backhaul link status from a NG-RAN node to an AMF of the core network. This figure shows a NG-RAN node 701 like WAB-gNB 532 (e.g. gNB component 532 of the WAB node 530) or BH-gNBl 501 (e.g. backhaul RAN node 501 serving WAB node 530) of figure 5, and an AMF 702 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. The NG-RAN node 701 may also be embedded in a satellite, like the satellite 160 of figure 1. It is assumed that a NG connection has been previously established between the NG-RAN node 701 and the AMF 702 (e.g. the AMF entity associated with or interacting with or connected to or having an active NG connection with the gNB component of the WAB node, which AMF entity may also be referred to as an AMF entity associated with or handling or serving a UE served by the WAB node or as a UE AMF entity). As discussed above, a UE AMF entity may be the same as a WAB AMF or BH AMF entity, which WAB AMF or BH AMF entity is the AMF entity associated with or connected to or serving or interacting with MT component of the WAB node. When the NG-RAN node 701 wants to provide the status or condition of a wireless backhaul link to the AMF 702, the NG-RAN node 701 sends a BH LINK STATUS message 703 to the AMF 702 (e.g. UE AMF entity). The status or condition of the wireless backhaul link may relate to one or more of: radio quality, congestion (e.g. congestion at the transmission buffer(s) at one end or side of the link or congestion at the transmission buffers at both ends or sides of the link, such as uplink congestion over the wireless backhaul link and / or downlink congestion over the wireless backhaul link). This message is sent through the NG-C interface previously setup between this NG-RAN node 701 and the AMF 702. The BH LINK STATUS message 703 may include one or more of the following information elements: - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value “backhaul link status indication”. For example, message type information for indicating the message includes information for indicating a condition or status of the wireless backhaul link is included in the message; An identifier of the NG-RAN node 701, for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5, as the identifier of the transmitter or sender of the message 703; An identifier of the wireless backhaul link for which the status is provided. The identifier or information for identifying the wireless backhaul link may be composed of at least one of: o An identifier of the NG-RAN node at one side of the wireless backhaul link (e.g. the backhaul RAN node serving the WAB-MT of a WAB node), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Global RAN Node ID. This identifier may not be present when it corresponds to the identifier of the transmitter of the message 703 (e.g. in the case where the transmitter of the message 703 is the NG-RAN node or backhaul RAN node serving the WAB-MT); o An identifier of the UE at one side of the wireless backhaul link (e.g. the WAB-MT of a WAB node), for instance the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1, assigned by the AMF 702 to the UE. This IE may be called the Backhaul UE ID; o An identifier of the NG-RAN node co-located with the UE at one side of the wireless backhaul link (e.g. the gNB component (WAB-gNB) of a WAB node colocated with the MT component of the WAB node at one side of the wireless backhaul link), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Colocated Global RAN Node ID. This identifier may not be present when it corresponds to the identifier of the transmitter of the message (e.g. in the case where the transmitter of the message 703 is the WAB-gNB of the WAB node and the WAB-MT of the WAB node is at one side of the wireless backhaul link); - Link Quality Information, which indicates the overall quality of the wireless backhaul link, for instance with an integer value ranging from 0 to 8, where the value 0 indicates the worse or lowest quality level (i.e. equivalent to a broken link or radio link failure) and the value 8 indicates the best or highest quality level or vice versa; Radio Link Quality Information, which indicates the radio quality of the wireless backhaul link (e.g. the measured RSRP or RSRQ at the receiver entity receiving radio signals transmitted on the wireless backhaul link); - Downlink Congestion Information, which indicates a level of congestion of the wireless backhaul link in downlink (i.e. data transmission from a core network to served UEs); - Uplink Congestion Information, which indicates a level of congestion of the wireless backhaul link in uplink (i.e. data transmission from served UEs to a core network); Long-Term Indication or information, which indicates whether the wireless backhaul link status is considered as stable (i.e. the current status has been established for a long time and / or will last (e.g. is expected to last) for a long time); Trend Indication, which indicates whether the link quality (e.g. status or condition of the wireless the backhaul link) is currently increasing or decreasing. There may be one trend indication per type of status (e.g. quality) information (i.e. radio link quality, uplink congestion, downlink congestion); Cause information, which indicates the cause of the status or condition, for instance the cause may be at least one of congestion, or poor radio conditions, or lack of radio resources. The BH LINK STATUS message 703 may be periodically sent, or only when a significant change of the wireless backhaul link is detected (and only when the change is stable). After reception of the BH LINK STATUS message 703 from the NG-RAN node 701, the AMF 702 may respond with the BH LINK STATUS RESPONSE message 705. The response message 705 may include information elements indicating the type of operation the AMF 702 may apply following the reception of message 703. For instance, the type of operation is to prioritize traffic to handle the mobility of served UEs (handover). The BH LINK STATUS message 703 and the BH LINK STATUS RESPONSE message 705 are NG protocol messages. The procedure of figure 7a may correspond to the RAN Configuration Update procedure described in TS 38.413 section 8.7.2, with the message 703 corresponding to the message RAN CONFIGURATION UPDATE (described in TS 38.413 section 9.2.6.4), and with the message 705 corresponding to the message RAN CONFIGURATION UPDATE ACKNOWLEDGE (described inTS 38.413 section 9.2.6.5). Figure 7b is a schematic diagram showing an example message flow 710 for performing a procedure for the notification of a wireless backhaul link status from a UE (e.g. MT component of a WAB node) to an AMF of the core network. This figure shows a UE 711 like WAB-MT 531 (e.g. MT component 531 of the WAB node 530) of figure 5, and an AMF 712 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It is assumed that the WAB-MT 531 is registered in the core network through the AMF 712 (e.g. the AMF entity associated with the MT component 531 of the WAB node 530, which AMF entity may also be referred to as the WAB AMF or BH AMF entity). The WAB AMF or BH AMF entity serves or interacts with or is connected to the MT component 531 of the WAB node. As discussed above, a WAB AMF or BH AMF entity may be the same as a UE AMF entity, which UE AMF entity is the AMF entity associated with or connected to or serving or interacting with or having an active NG connection with the gNB component of the WAB node and handling or serving the UEs served by the gNB component. When the UE 711 wants to provide the status or condition of a wireless backhaul link to the AMF 712, the UE 711 sends a BH LINK STATUS message 713 to the AMF 712 (e.g. WAB AMF or BH AMF). The status or condition of the wireless backhaul link may relate to one or more of radio quality, congestion (e.g. congestion at the transmission buffer(s) at one end or side of the link or congestion at the transmission buffers at both ends or sides of the link, such as uplink congestion over the wireless backhaul link and / or downlink congestion over the wireless backhaul link). This message is a NAS protocol message sent over the NG-C interface previously setup between the backhaul RAN node serving the UE 711 (or BH RAN node e.g. BH-gNBl 501 of figure 5) and the AMF 712. The BH LINK STATUS message 703 may include one or more of the following information elements: - Message Type, as defined in TS 24.501 section 9.7, for instance with the value “backhaul link status indication”. For example, message type information for indicating the message includes information for indicating a condition or status of the wireless backhaul link is included in the message; An identifier of the UE 711, for instance the 5GS mobile identity defined in TS 24.501 section 9.11.3.4, as the identifier of the transmitter or sender of the message 713; An identifier of the wireless backhaul link for which the status is provided. The identifier or information for identifying the wireless backhaul link may be composed of at least one of o An identifier of the UE at one side of the wireless backhaul link (e.g. the WAB-MT of a WAB node), for instance the 5GS mobile identity defined in TS 24.501 section 9.11.3.4. This IE may be called the Backhaul UE ID. This identifier may not be present when it corresponds to the identifier of the transmitter of the message 713 (e.g. in the case where the transmitter of the message 713 is the WAB-MT of the WAB node); o An identifier of the NG-RAN node at one side of the wireless backhaul link (e.g. the backhaul RAN node serving the WAB-MT of a WAB node), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Global RAN Node ID; o An identifier of the NG-RAN node co-located with the UE at one side of the wireless backhaul link (e.g. the gNB component (WAB-gNB) of a WAB node colocated with the MT component of the WAB node at one side of the wireless backhaul link), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Colocated Global RAN Node ID; - Link Quality Information, which indicates the overall quality of the wireless backhaul link, for instance with an integer value ranging from 0 to 8, where the value 0 indicates the worse or lowest quality level (i.e. equivalent to a broken link or radio link failure) and the value 8 indicates the best or highest quality level or vice versa; - Radio Link Quality Information, which indicates the radio quality of the wireless backhaul link (e.g. the measured RSRP or RSRQ at the receiver entity receiving radio signals transmitted on the wireless backhaul link); - Downlink Congestion Information, which indicates a level of congestion of the wireless backhaul link in downlink (i.e. data transmission from a core network to served UEs); - Uplink Congestion Information, which indicates a level of congestion of the wireless backhaul link in uplink (i.e. data transmission from served UEs to a core network); Long-Term Indication or information, which indicates whether the wireless backhaul link status is considered as stable (i.e. the current status has been established for a long time and / or will last (or is expected to last) for a long time); Trend Indication, which indicates whether the link quality (e.g. status or condition of the wireless backhaul link) is currently increasing or decreasing. There may be one trend indication per type of status (e.g. quality) information (i.e. radio link quality, uplink congestion, downlink congestion); Cause information, which indicates the cause of the status or condition, for instance the cause is congestion, or poor radio conditions, or lack of radio resources. The BH LINK STATUS message 713 may be periodically sent, or only when a significant change of the wireless backhaul link is detected (and only when the change is stable). After reception of the BH LINK STATUS message 713 from the UE 711, the AMF 712 may respond with the BH LINK STATUS RESPONSE message 715. The response message 715 may include information elements indicating the type of operation the AMF 712 may apply following the reception of message 713. For instance, the type of operation is to prioritize traffic to handle the mobility of served UEs (handover). The BH LINK STATUS message 713 and the BH LINK STATUS RESPONSE message 715 are NG protocol messages. Figure 8a is a schematic diagram showing an example message flow 800 for performing a procedure for the notification of a wireless backhaul link status from a UE (e.g. a MT component of a WAB node) to a NG-RAN node (such as a backhaul RAN node serving the WAB node). This figure shows a UE 801 like WAB-MT 531 (e.g. MT component 531 of the WAB node 530) of figure 5a, and aNG-RAN node 802 like BH-gNBl 501 of figure 5. The NG-RAN node 802 may also be embedded in a satellite, like the satellite 160 of figure 1. It is assumed that a RRC connection has been previously established between the UE 801 and the NG-RAN node 802 (e.g. the MT component 531 of the WAB node 530 is connected to or has an active RRC connection with the backhaul RAN node serving the WAB node 530). When the UE 801 wants to provide the status or condition of a wireless backhaul link to the NG-RAN node 802, the UE 801 sends a BH LINK STATUS message 803 to the NG-RAN node 802. The status or condition of the wireless backhaul link may relate to one or more of: radio quality, congestion (e.g. congestion at the transmission buffer(s) at one end or side of the link or congestion at the transmission buffers at both ends or sides of the link, such as uplink congestion over the wireless backhaul link and / or downlink congestion over the wireless backhaul link). This RRC protocol message is sent through the Uu interface previously setup between this UE 801 and the NG-RAN node 802. The BH LINK STATUS message 803 may include one or more of the following information elements: - Message Type for instance with the value “backhaul link status indication”. For example, message type information for indicating the message includes information for indicating a condition or status of the wireless backhaul link is included in the message; An identifier of the UE 801, for instance a RNTI (Radio Network Temporary Identifier) as defined in TS 38.331 assigned by the NG-RAN node 802, as the identifier of the transmitter or sender of the message 803; An identifier of the wireless backhaul link for which the status is provided. The identifier or information for identifying the wireless backhaul link may be composed of at least one of: o An identifier of the UE at one side of the wireless backhaul link (e.g. the WAB-MT of a WAB node), for instance the AMF UENGAP ID defined in TS 38.413 section 9.3.3.1, assigned by the AMF serving the UE. This IE may be called the Backhaul UE ID. This identifier may not be present when it corresponds to the identifier of the transmitter of the message 803 (e.g. in the case where the transmitter of the message 803 is UE 801); o An identifier of the NG-RAN node co-located with the UE at one side of the wireless backhaul link (e.g. the gNB component (WAB-gNB) of a WAB node colocated with the MT component of the WAB node at one side of the wireless backhaul link), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Colocated Global RAN Node ID; - Link Quality Information, which indicates the overall quality of the wireless backhaul link, for instance with an integer value ranging from 0 to 8, where the value 0 indicates the worse or lowest quality level (i.e. equivalent to a broken link or radio link failure) and the value 8 indicates the best or highest quality level or vice versa; - Radio Link Quality Information, which indicates the radio quality of the wireless backhaul link (e.g. the measured RSRP or RSRQ at the receiver entity receiving radio signals transmitted on the wireless backhaul link); - Downlink Congestion Information, which indicates a level of congestion of the wireless backhaul link in downlink (i.e. data transmission from a core network to served UEs); - Uplink Congestion Information, which indicates a level of congestion of the wireless backhaul link in uplink (i.e. data transmission from served UEs to a core network); Long-Term Indication or information, which indicates whether the wireless backhaul link status is considered as stable (i.e. the current status has been established for a long time and / or will last (or is expected to last) for a long time); Trend Indication, which indicates whether the link quality (e.g. status or condition of the wireless the backhaul link) is currently increasing or decreasing. There may be one trend indication per type of status (e.g. quality) information (i.e. radio link quality, uplink congestion, downlink congestion); Cause information, which indicates the cause of the status or condition, for instance the cause is congestion, or poor radio conditions, or lack of radio resources. The BH LINK STATUS message 803 may be periodically sent, or only when a significant change of the wireless backhaul link is detected (and only when the change is stable). After reception of the BH LINK STATUS message 803 from the UE 801, the NG-RAN node 802 may respond with the BH LINK STATUS RESPONSE message 805. The response message 805 may include information elements indicating the type of operation the NG-RAN node 802 may apply following the reception of message 803. For instance, the type of operation is to increase the resources in uplink to cope with a congestion in uplink. The NG-RAN node 802 may also forward the wireless backhaul link status received in the message 803 to the AMF serving the UE (e.g. WAB-MT) at one side of the wireless backhaul link, which AMF may be referred to as the WAB AMF or BH AMF entity associated with or serving or interacting with the MT component of the WAB node, and / or to the AMF(s) connected to the NG-RAN node (e.g. WAB-gNB) co-located to the UE at one side of the wireless backhaul link, which AMF(s) may be referred to as the UE AMFs associated with or connected to or interacting with the gNB component of the WAB node and serving or handling the UEs served by the gNB component of the WAB node. The BH LINK STATUS message 803 and the BH LINK STATUS RESPONSE message 805 are RRC protocol messages. The BH LINK STATUS message 803 may be the existing UEAssistancelnformation message, defined in TS 38.331 and amended with some or all of the information elements listed above. According to another embodiment, the message 803 of figure 8a is sent by the NG-RAN node 802 to the UE 801. For instance, a BH RAN node (i.e. the NG RAN node 802) serving a WAB-MT (i.e. the UE 801) of a WAB node, may inform the WAB-MT about a downlink congestion of the wireless backhaul link between the WAB-MT and BH RAN node, using the BH LINK STATUS message 803. In that case, the identifier of the message 803 is an identifier of the NG-RAN node 801, which may be the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node 801. Figure 8b is a schematic diagram showing an example message flow 810 for performing a procedure for the notification of a wireless backhaul link status from a first NG RAN node to a second NG-RAN node. For example, the first NG-RAN node may be a gNB component of a WAB node and the second NG-RAN node may be a backhaul RAN node serving the MT component of the WAB node or one or more RAN nodes neighbouring the WAB node. In another example, the first NG-RAN node may be a backhaul RAN node serving the MT component of the WAB node and the second NG-RAN node may be the gNB component of the WAB node or one or more RAN nodes neighbouring the WAB node and other than the backhaul RAN node. This figure shows two NG-RAN nodes 811 and 812 like WAB-gNB 532 and BH-gNBl 501, or like BH-gNB 1 501 andBH-gNB2 502 of figure 5. The NG-RAN node 812 may also be embedded in a satellite, like the satellite 160 of figure 1. It is assumed that a Xn connection has been previously established between the NG-RAN nodes 811 and 812. When the NG-RAN node 811 wants to provide the status or condition of a wireless backhaul link to the NG-RAN node 812, the NG-RAN node 811 sends a BH LINK STATUS message 813 to the NG-RAN node 812. The status or condition of the wireless backhaul link may relate to one or more of: radio quality, congestion (e.g. congestion at the transmission buffer(s) at one end or side of the link or congestion at the transmission buffers at both ends or sides of the link, such as uplink congestion over the wireless backhaul link and / or downlink congestion over the wireless backhaul link). This message is sent through the Xn interface previously setup between the NG-RAN nodes 811 and 812. The BH LINK STATUS message 813 may include one or more of the following information elements: - Message Type, as defined in TS 38.423 section 9.2.3.1, for instance with the value “backhaul link status indication”. For example, message type information for indicating the message includes information for indicating a condition / status of the wireless backhaul link is included in the message; An identifier of the NG-RAN node 811, for instance the Global RAN Node ID as defined in TS 38.423 section 9.2.2.3, as the identifier of the transmitter or sender of the message 813; An identifier of the wireless backhaul link for which the status is provided. The identifier or information for identifying the wireless backhaul link may be composed of at least one of: o An identifier of the NG-RAN node co-located with the UE at one side of the wireless backhaul link (e.g. the gNB component (WAB-gNB) of a WAB node colocated with the MT component of the WAB node at one side of the wireless backhaul link), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node, this IE may be called the Backhaul Colocated Global RAN Node ID. This identifier may not be present when it corresponds to the identifier of the transmitter of message 813 (e.g. in the case where the transmitter of the message 813 is the NG-RAN node 811); o An identifier of the NG-RAN node at one side of the wireless backhaul link (e.g. the backhaul RAN node serving the WAB-MT of a WAB node), for instance the Global RAN Node ID as defined in TS 38.423 section 9.2.2.3. This IE may be called the Backhaul Global RAN Node ID. This identifier may be the same as the identifier of the NG-RAN node 811; o An identifier of the UE at one side of the wireless backhaul link (e.g. the WAB-MT of a WAB node co-located with the NG-RAN node in the WAB node), for instance the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1, assigned by the AMF serving the UE. This IE may be called the Backhaul UE ID; - Link Quality Information, which indicates the overall quality of the wireless backhaul link, for instance with an integer value ranging from 0 to 8, where the value 0 indicates the worse or lowest quality level (i.e. equivalent to a broken link or radio link failure) and the value 8 indicates the best or highest quality level or vice versa; - Radio Link Quality Information, which indicates the radio quality of the wireless backhaul link (e.g. the measured RSRP or RSRQ at the receiver entity receiving radio signals transmitted on the wireless backhaul link); - Downlink Congestion Information, which indicates a level of congestion of the wireless backhaul link in downlink (i.e. data transmission from a core network to served UEs); - Uplink Congestion Information, which indicates a level of congestion of the wireless backhaul link in uplink (i.e. data transmission from served UEs to a core network); Long-Term Indication or information, which indicates whether the wireless backhaul link status is considered as stable (i.e. the current status has been established for a long time and / or will last (or is expected to last) for a long time); Trend Indication, which indicates whether the link quality (e.g. status or condition of the wireless the backhaul link) is currently increasing or decreasing. There may be one trend indication per type of status (e.g. quality) information (i.e. radio link quality, uplink congestion, downlink congestion); Cause information, which indicates the cause of the status or condition, for instance the cause is congestion, or poor radio conditions, or lack of radio resources. The BH LINK STATUS message 813 may be periodically sent, or only when a significant change of the wireless backhaul link is detected (and only when the change is stable). After reception of the BH LINK STATUS message 813 from the NG-RAN node 811, the NG-RAN node 812 may respond with the BH LINK STATUS RESPONSE message 815. The response message 815 may include information elements indicating the type of operation the NG-RAN node 812 may apply following the reception of message 813. For instance, the operation (e.g. at a backhaul RAN node at one side of the wireless backhaul link) is to increase the resources in uplink to cope with a congestion in uplink. The NG-RAN node 812 may also forward the wireless backhaul link status received in the message 813 to the AMF serving the UE (e.g. WAB-MT) at one side of the wireless backhaul link, which AMF may be referred to as the WAB AMF or BH AMF entity associated with or serving or interacting with the MT component of the WAB node, and / or to the AMF(s) connected to the NG-RAN node (e.g. WAB-gNB) co-located to the UE at one side of the wireless backhaul link, which AMF(s) may be referred to as the UE AMFs associated with or connected to or interacting with the gNB component of the WAB node and serving or handling the UEs served by the gNB component of the WAB node. The BH LINK STATUS message 813 and the BH LINK STATUS RESPONSE message 815 are Xn protocol messages. The procedure of figure 8b may correspond to the NG-RAN node Configuration Update procedure described in TS 38.423 section 8.4.2, with the message 813 corresponding to the message NG-RAN NODE CONFIGURATION UPDATE (described in TS 38.423 section 9.1.3.4), and with the message 815 corresponding to the message NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE (described in TS 38.423 section 9.1.3.5). Figure 9a is a schematic diagram showing an example message flow 900 for performing a procedure for a UE (e.g. MT component of a WAB node) to provide to a NG-RAN node a list of AMFs involved in a wireless backhaul link. For example, the MT component of the WAB node may provide, to a backhaul RAN node serving the MT component, AMF information identifying one or more AMF entities associated with the WAB node. The one or more AMF entities associated with the WAB node include at least one of: one or more AMF entities connected to the gNB component of the WAB node; and an AMF entity serving the MT component of the WAB node. This figure shows a UE 901 like WAB-MT 531 (e.g. MT component 531 of the WAB node 530) of figure 5a, and aNG-RAN node 902 like BH-gNBl 501 of figure 5. The NG-RAN node 902 may also be embedded in a satellite, like the satellite 160 of figure 1. It is assumed that a RRC connection has been previously established between the UE 901 and the NG-RAN node 902. When the UE 901 wants to provide a list of AMFs (e.g. AMF information) to the NG-RAN node 902, the UE 901 sends a CONFIGURATION UPDATE message 903 to the NG-RAN node 902. This RRC protocol message is sent through the Uu interface previously setup between this UE 901 and the NG-RAN node 902. The CONFIGURATION UPDATE message 903 may include one or more of the following information elements: - Message Type for instance with the value “AMF indication”. For example, message type information for indicating the message includes information identifying one or more AMF entities associated with the WAB node is included in the message; An identifier of the UE 901, for instance a RNTI (Radio Network Temporary Identifier) as defined in TS 38.331 assigned by the NG-RAN node 902, as the identifier of the transmitter or sender of the message 903; An identifier of the wireless backhaul link for which the list of involved AMFs is provided. The identifier or information for identifying the wireless backhaul link may be composed of at least one of o An identifier of the UE at one side of the wireless backhaul link (e.g. the WAB-MT of a WAB node), for instance the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1, assigned by the AMF serving the UE. This IE may be called the Backhaul UE ID. This identifier may not be present when it corresponds to the identifier of the transmitter of the message 903 (e.g. in the case where the transmitter of the message 903 is UE 901); o An identifier of the NG-RAN node co-located with the UE at one side of the wireless backhaul link (e.g. the gNB component (WAB-gNB) of a WAB node colocated with the MT component of the WAB node at one side of the wireless backhaul link), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Colocated Global RAN Node ID; An identifier of the AMF serving the UE at one side of the wireless backhaul link (e.g. the WAB AMF or BH AMF), for instance the corresponding GUAMI as defined in TS 38.413 section 9.3.3.3. This IE may be called the BH AMF ID; An identifier of the AMF(s) connected to the NG-RAN node (e.g. gNB component of the WAB node) co-located with the UE at one side of the wireless backhaul link (which AMF(s) may be referred to as the UE AMF(s) associated with or connected to or interacting with the gNB component of the WAB node and serving or handling the UEs served by the gNB component of the WAB node), for instance with a list of GUAMI as defined in TS 38.413 section 9.3.3.3. This IE may be called the UE AMF ID List. The CONFIGURATION UPDATE message 903 may be periodically sent, or only when a new AMF identifier shall be added to the list of AMF identifiers or when an AMF identifier shall be removed from the list of AMF identifiers. To avoid sending the whole list each time a UE AMF identifier is added or removed, a dedicated IE called “UE AMF ID to Add List” may be included in the message 903 to add one or several AMF identifiers in the UE AMF ID List, and a dedicated IE called “UE AMF ID to Remove List” may be included in the message 903 to remove one or several AMF identifiers from the UE AMF ID List. After reception of the CONFIGURATION UPDATE message 903 from the UE 901, the NG-RAN node 902 may respond with the CONFIGURATION UPDATE RESPONSE message 905. The CONFIGURATION UPDATE message 903 and the CONFIGURATION UPDATE RESPONSE message 905 are RRC protocol messages. The CONFIGURATION UPDATE message 903 may be the existing UEAssistancelnformation message, defined in TS 38.331 and amended with some or all of the information elements listed above. Figure 9b is a schematic diagram showing an example message flow 910 for performing a procedure for a first NG-RAN node to provide to a second NG-RAN node a list of AMFs involved in a wireless backhaul link. For example, the gNB component of the WAB node may provide, to a backhaul RAN node serving the MT component of the WAB node, AMF information identifying one or more AMF entities associated with the WAB node. The one or more AMF entities associated with the WAB node include at least one of one or more AMF entities connected to the gNB component of the WAB node; and an AMF entity serving the MT component of the WAB node. This figure shows two NG-RAN nodes 911 and 912 like WAB-gNB 532 (e.g. gNB component 532 of the WAB node 530) and BH-gNBl 501, of figure 5. The NG-RAN node 912 may also be embedded in a satellite, like the satellite 160 of figure 1. It is assumed that a Xn connection has been previously established between the NG-RAN nodes 911 and 912. When the NG-RAN node 911 wants to provide a list of AMFs (e.g. AMF information) to the NG-RAN node 912, the NG-RAN node 911 sends a CONFIGURATION UPDATE message 913 to the NG-RAN node 912. This Xn protocol message is sent through the Xn interface previously setup between this NG-RAN nodes 911 and 912. The CONFIGURATION UPDATE message 913 may include one or more of the following information elements: - Message Type for instance with the value “AMF indication”. For example, message type information for indicating the message includes information identifying one or more AMF entities associated with the WAB node is included in the message; An identifier of the NG-RAN node 911, for instance the Global RAN Node ID as defined in TS 38.423 section 9.2.2.3, as the identifier of the transmitter or sender of the message 913; An identifier of the wireless backhaul link for which the list of involved AMFs is provided. The identifier or information for identifying the wireless backhaul link may be composed of at least one of o An identifier of the UE at one side of the wireless backhaul link (e.g. the WAB-MT of a WAB node), for instance the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1, assigned by the AMF serving the UE. This IE may be called the Backhaul UE ID; o An identifier of the NG-RAN node co-located with the UE at one side of the wireless backhaul link (e.g. the gNB component (WAB-gNB) of a WAB node colocated with the MT component of the WAB node at one side of the wireless backhaul link), for instance the Global RAN Node ID as defined in TS 38.413 section 9.3.1.5 of this NG-RAN node. This IE may be called the Backhaul Colocated Global RAN Node ID. This IE may not be present when it corresponds to the identifier of the transmitter of the message 913 (e.g. in the case where the transmitter of message 913 is the NG-RAN node 911; An identifier of the AMF serving the UE at one side of the wireless backhaul link (e.g. the WAB AMF or BH AMF), for instance the corresponding GUAMI as defined in TS 38.413 section 9.3.3.3. This IE may be called the BH AMF ID; An identifier of the AMF(s) connected to the NG-RAN node (e.g. gNB component of the WAB node) co-located with the UE at one side of the wireless backhaul link (which AMF(s) may be referred to as the UE AMF(s) associated with or connected to or interacting with the gNB component of the WAB node and serving or handling the UEs served by the gNB component of the WAB node), for instance with a list of GUAMI as defined in TS 38.413 section 9.3.3.3. This IE may be called the UE AMF ID List. The CONFIGURATION UPDATE message 913 may be periodically sent, or only when a new AMF identifier shall be added to the list of AMF identifiers or when an AMF identifier shall be removed from the list of AMF identifiers. To avoid sending the whole list each time a UE AMF identifier is added or removed, a dedicated IE called “UE AMF ID to Add List” may be included in the message 903 to add one or several AMF identifiers in the UE AMF ID List, and a dedicated IE called “UE AMF ID to Remove List” may be included in the message 903 to remove one or several AMF identifiers from the UE AMF ID List. After reception of the CONFIGURATION UPDATE message 913 from the NG-RAN node 911, the NG-RAN node 912 may respond with the CONFIGURATION UPDATE RESPONSE message 915. The CONFIGURATION UPDATE message 913 and the CONFIGURATION UPDATE RESPONSE message 915 are Xn protocol messages. Methods for use in managing link status (e.g. managing notification of link status or providing link status) of a wireless backhaul link in a wireless network including a WAB node, in accordance with one or more embodiments of the invention will now be described with reference to the figures and in particular to the example methods described with reference to figure 10 and 11. The methods in accordance with the present invention may be performed by software elements and / or hardware elements. The network entity sending or receiving the backhaul link status information or notification (e.g. UE, NG-RAN node or AMF) may be implemented in a network node 400 as shown in and described with reference to figure 4, with the methods being performed by an apparatus for the network entity (e.g. UE, NG-RAN node or AMF) including one or more processing units, such as the processing unit 402. Figure 10 relates to a network entity associated with the WAB node sending information or a notification for indicating a link status of a wireless backhaul link supporting one or more Radio Access Network, RAN, interfaces associated with the WAB node. Figure 11 relates to a network entity associated with the WAB node receiving information or a notification for indicating a link status of a wireless backhaul link supporting one or more Radio Access Network, RAN, interfaces associated with the WAB node. A network entity or first network entity sending information for indicating a link status of a wireless backhaul link (which is also referred to as backhaul link status information) may be one of a NG-RAN node (e.g. a NG-RAN node associated with the wireless backhaul link) and a MT component or UE of the WAB node which is at one side or end of the wireless backhaul link. The NG-RAN node may be a backhaul RAN node serving the WAB node over the backhaul link (e.g. the backhaul RAN node is serving the MT component or UE of the WAB node and may be considered as being at or connected to one side or end of the backhaul link) or a gNB component of the WAB node which is at one side or end of the wireless backhaul link. The NG-RAN node may send backhaul link status information to one or more AMF entities associated with the WAB node (for example as described with reference to figure 7a above) and / or to one or more other NG-RAN nodes neighbouring the WAB node (for example as described with reference to figure 8b above). In the case where the NG-RAN node sending backhaul link status information is a gNB component of the WAB node, the one or more other NG-RAN nodes receiving the backhaul link status information is a backhaul RAN node serving the WAB node over the backhaul link. In the case where the NG-RAN node sending backhaul link status information is a backhaul RAN node serving the WAB node over the backhaul link, the one or more other NG-RAN nodes receiving the backhaul link status information are one or more NG-RAN nodes neighbouring or in the vicinity of the WAB node other than the backhaul WAB node (for example as described with reference to figure 8b above). Thus, a backhaul RAN node serving a WAB node over a wireless backhaul link may send the backhaul link status information to one or more AMF entities associated with the WAB node (for example as described with reference to figure 7a above) and / or to one or more other NG-RAN nodes neighbouring the WAB node (for example as described with reference to figure 8b above). A gNB component of a WAB node may send the backhaul link status information to one or more AMF entities associated with the WAB node (for example as described with reference to figure 7a above) and / or to one or more NG-RAN nodes neighbouring the WAB node including a backhaul RAN node serving the WAB node over the backhaul link. The gNB component of the WAB node may send the backhaul link status information to the backhaul RAN node serving the WAB node over the backhaul link and other neighbouring NG-RAN nodes, e.g. to NG-RAN nodes having a Xn connection with the WAB-gNB. Sending the backhaul link status information to neighbouring RAN nodes may help to reduce Xn traffic in case of backhaul link degradation. A MT component or UE of a WAB node may send backhaul link status information to a backhaul RAN node serving the WAB node over the wireless backhaul link (for example as described with reference to figure 8a above) and / or to one or more AMF entities associated with the WAB node (for example as described with reference to figure 7b above). The information (e.g. backhaul link status information and / or identification information) sent by the first network entity may be determined or detected or provided by the first network entity and / or may be at least partly based on information received from another network entity (e.g. a third network entity which is another network entity to a network entity / second network entity receiving the information). For example, the MT component of the WAB node and / or a backhaul RAN node serving the WAB node over the backhaul link may perform measurements on the wireless backhaul link to determine or detect link quality, radio link quality, congestion etc.. The first network entity may determine a change in link status of the wireless backhaul link based on the determinati on / detecti on. For example, the information (e.g. backhaul link status information and / or identification information) sent by the gNB component of the WAB node may be partly based on information received at or provided to the gNB component of the WAB node from the MT component of the WAB node over an internal interface (e.g. the information received at the gNB component from the MT component may include link quality information, and / or radio link quality information, and / or congestion information as determined or detected at the MT component, identifier of MT component). The information received from the MT component may also include downlink status information (e.g. downlink congestion information) as determined or detected at the backhaul RAN node serving the WAB node over the wireless backhaul link and forwarded to the gNB component by the MT component. The gNB component of the WAB node will have received at least the identifiers of one or more UE AMF entities on establishing a NG connection with such AMF entities. For example, the information (e.g. backhaul link status information and / or identification information) sent from the MT component of the WAB node may be partly based on status information determined or detected or provided by the MT component of the WAB node (e.g. link quality information, radio link quality information, congestion information as determined or detected at the MT component). The information may also include downlink status information (e.g. downlink congestion information) as determined or detected at the backhaul RAN node serving the WAB node over the wireless backhaul link and received at the MT component. The MT component of the WAB node will have received at least the identifier of the WAB or BH UE AMF entity on establishing a connection with the AMF entity. For example, the information (e.g. backhaul link status information and / or identification information) sent by the backhaul RAN node may be partly based on information received from the MT component of the WAB node (e.g. link quality information, and / or radio link quality information, and / or congestion information as determined or detected at the MT component, identifier of MT component, identifier of MT component). The information received from the MT component may also include information (e.g. UE AMF entity identification information) as provided by the gNB component of the WAB node and forwarded to the MT component by the gNB component. The backhaul link status information may be sent periodically or after detecting a change (e.g. a significant change and once the status has stabilised) in link status of the wireless backhaul link. The first network entity may receive a response. The response may be sent in a message such as the BH LINK STATUS Response message 705, 715, 805, 815. In the case where the information for indicating a link status of the wireless backhaul link is sent to at least one AMF entity, (e.g. an AMF entity (WAB or BH AMF entity) connected to the MT component of the WAB node and / or one or more AMF entities (UE AMF entity(s)) connected to the gNB component of the WAB node), the first network entity receives a response from the at least one AMF entity and the response includes information indicating an operation or action (or type of operation or action) the respective AMF entity may perform or apply after receiving the information for indicating a link status of the wireless backhaul link. For example, the operation / action the AMF entity may apply or perform may be to prioritize traffic to handle the mobility of served UEs (handover). The response may be sent in message 705, 715 as described with reference to figures 7a and 7b. In the case where the information for indicating a link status of the wireless backhaul link is sent by the MT component of the WAB node to a backhaul RAN node serving the WAB node over the backhaul wireless link, the MT component of the WAB node receives a response from the backhaul RAN node and the response includes information indicating an operation or action (or type of operation or action) the backhaul RAN node may perform or apply after receiving the information for indicating a link status of the wireless backhaul link. For example, the operation / action the backhaul RAN node may apply or perform may be to increase the resources in uplink to cope with a congestion in uplink. The response may be sent in message 805 as described with reference to figure 8a. In the case where the information for indicating a link status of the wireless backhaul link is sent by a NG-RAN node or first NG-RAN node to another NG-RAN node or second NG-RAN node, the first NG-RAN node receives a response from the second NG-RAN node and the response includes information indicating an operation or action (or type of operation or action) the second NG-RAN node may perform or apply after receiving the information for indicating a link status of the wireless backhaul link. For example, the operation / action the second NG-RAN node may apply or perform may be to increase the resources in uplink to cope with a congestion in uplink. The response may be sent in message 805 as described with reference to figure 8b. In the case where the network entity or first network entity sending the information indicating a link status of the wireless backhaul link is at least one of: the MT component of the WAB node; a backhaul RAN node serving the WAB node, the first network entity may also receive information or AMF information identifying one or more AMF entities associated with the WAB node and / or associated with the wireless backhaul link. For example, such an AMF entity is associated with traffic transmitted over or through the wireless backhaul link and is involved with generating and / or scheduling and / or transmitting traffic on the wireless backhaul link. The AMF entity may be at least one of a WAB or BH AMF entity or one or more UE AMF entities. The information identifying one or more AMF entities may be sent to the first network entity (e.g. the backhaul RAN node) by the MT component or UE of the WAB node and may include information for the BH AMF entity and one or more UE AMF entities as described with reference to message 903 and figure 9a. The information identifying one or more AMF entities may be sent to the first network entity (e.g. the MT component of the WAB node or the backhaul RAN node) by the gNB component of the WAB node and may include information for the one or more UE AMF entities as described with reference to message 913 and figure 9ba. The AMF information may include an identifier for each of one or more AMF entities associated with the WAB node, such as the BH AMF ID and / or UE AMF ID List as described above. The AMF information may be sent in a message (such as message 903 and 913) which message may also include at least one of: message type information for indicating the message includes information indicating a link status of the wireless backhaul link (e.g. Message Type IE as discussed above); information for identifying the network entity sending or transmitting the message (e.g. an IE including an identifier of the NG-RAN node, such as a Global RAN Node ID, or the UE / MT component of the WAB node, such as the 5GS mobile identity as discussed above); information for identifying the wireless backhaul link. The information for identifying the wireless backhaul link includes at least one of: an identifier, such as a Global RAN Node ID, of a backhaul RAN node serving the WAB node, the backhaul RAN node may be at one side or end of the wireless backhaul link or may be serving the WAB node over the wireless backhaul link (e.g. the Backhaul Global RAN Node ID as described above); an identifier of the MT component or UE of the WAB node, which MT component or UE is at one side of the wireless backhaul link (e.g. the Backhaul UE ID as described above); an identifier of the gNB component of the WAB node colocated with the MT component or UE of the WAB node (e.g. the Backhaul Co-located Global RAN Node ID as described above). The AMF information may be sent periodically or when the AMF information identifying the one or more AMF entities is to be updated. As discussed above with reference to figures 9a and 9b, the AMF information may be updated or changed to add or remove the identifier(s) of one or more AMF entities, for example, using an “UE AMF ID to Add List” or “UE AMF ID to Remove List”. The backhaul link status information may be sent or received in one or more of messages 703, 713, 803, 813 as discussed herein. The link status or link condition of a wireless backhaul link may also be referred to as backhaul link status or backhaul link condition. The link status / condition may indicate the current status / condition and as such, may indicate a change in status or condition. The one or more RAN interfaces include at least one of: a Xn interface associated with the gNB component of the WAB node; a NG interface associated with the gNB component of the WAB node; a NR Uu interface associated with the MT component of the WAB node. The information for indicating a link status of a wireless backhaul link may include at least one of: link quality information or first quality information for indicating an overall quality of the wireless backhaul link (e.g. the Link Quality Information IE as discussed above); radio link quality information or second quality information for indicating radio quality of the wireless backhaul link (e.g. the Radio Link Quality Information IE as discussed above); congestion information for indicating a level of congestion of or at the wireless backhaul link or load information for indicating a level of load at the wireless backhaul link (e.g. the Downlink Congestion Information IE and / or the Uplink Congestion Information IE as discussed above); information for indicating whether the wireless backhaul link status is stable, that is whether the wireless backhaul link status is considered as stable and hasn’t changed or has been substantially the same for a certain period of time (e.g. the Long-Term Indication IE as discussed above); information for indicating whether a link quality (e.g. radio quality and / or congestion, etc.) of the wireless backhaul link is increasing or decreasing (e.g. the Trend Indication IE as discussed above); cause information for indicating a cause or reason for the link status of the wireless backhaul link (e.g. Cause information IE as discussed above). In an example, the link quality information has one of a plurality of values for indicating an overall level of quality of the wireless backhaul link, each value of the plurality of values representing a certain level of quality. The plurality of values may include predetermined values over a range, where one end of the range represents the best or highest quality level and the other end represents the worse or lowest quality level. A message (such as one or more of messages 703, 713, 803, 813) including the information indicating a link status of a wireless backhaul link may also include at least one of: message type information for indicating the message includes information indicating a link status of the wireless backhaul link (e.g. Message Type IE as discussed above); information for identifying the network entity sending the message (e.g. an IE including an identifier of the NG-RAN node, such as a Global RAN Node ID, or the UE / MT component of the WAB node, such as the 5GS mobile identity as discussed above); information for identifying the wireless backhaul link. The information for identifying the wireless backhaul link includes at least one of: an identifier, such as a Global RAN Node ID, of a backhaul RAN node serving the WAB node, the backhaul RAN node may be at one side or end of the wireless backhaul link or may be serving the WAB node over the wireless backhaul link (e.g. the Backhaul Global RAN Node ID as described above); an identifier of the MT component or UE of the WAB node, which MT component or UE is at one side of the wireless backhaul link (e.g. the Backhaul UE ID as described above); an identifier of the gNB component of the WAB node co-located with the MT component or UE of the WAB node (e.g. the Backhaul Colocated Global RAN Node ID as described above). The above description relating to a network entity sending information (e.g. the backhaul link status information and / or the identification information and / or AMF information) may also be applied to another network entity receiving the sent information and a detailed description for a method of receiving will not be repeated here. Similarly, the above description relating to a network entity receiving a response may also be applied to another network entity receiving the sent information and sending the response and a detailed description for a method of sending the response will not be repeated here. The network entity or second network entity receiving the information (e.g. the backhaul link status information and / or the identification information and / or AMF information) is another network entity associated with the WAB node and / or associated with the wireless backhaul link and / or are associated with traffic transmitted over the wireless backhaul link (e.g. a network entity which generates and / or schedules and / or transmits traffic on or through or over or via the wireless backhaul link). For example, the second network entity associated with the wireless backhaul link and receiving the information may be a network entity that is associated with traffic transmitted over or through the wireless backhaul link e.g. which generate and / or schedule and / or transmit traffic on the wireless backhaul link). The second network entity may be at least one of: one or more AMF entities associated with traffic transmitted over or through the wireless backhaul link, such as a UE AMF entity serving the MT component or UE of the WAB node and / or one or more WAB or BH AMF entities serving the gNB component of the WAB node; one or more NG-RAN nodes associated with the WAB node. In this case the one or more NG-RAN nodes may be a backhaul RAN node serving the WAB node over the backhaul link (e.g. the backhaul RAN node is serving the MT component or UE of the WAB node and may be considered as being at or connected to one side or end of the backhaul link) or one or more other NG-RAN nodes neighbouring or in the vicinity of the WAB node. A backhaul RAN node serving a WAB node may receive backhaul link status information from the gNB component of the WAB node and / or the MT component or UE of the WAB node. One or more neighbouring NG-RAN nodes of a WAB node may receive backhaul link status information from the gNB component of the WAB node and / or a backhaul RAN node serving the WAB node. In the case where the network entity receiving the information (e.g. the backhaul link status information and / or the identification information and / or AMF information) is a backhaul RAN node serving the WAB node, the backhaul RAN node may send or forward, to one or more AMF entities associated with the WAB node or one or more other NG-RAN nodes neighbouring the WAB node, information for indicating the link status of the wireless backhaul link based on the information received at the backhaul RAN node. Referring now also to Figure 10 which is a flowchart of an example method 1000 for managing at a network entity associated with the WAB node, such as a UE or MT component of a WAB node or a NG-RAN node, such as a gNB component of a WAB node or a backhaul RAN node serving the MT component of the WAB node, the notification of a backhaul link status to another network entity associated with the backhaul link or WAB node, such as an AMF (WAB or BH AMF and / or UE AMF(s) of the WAB node) or a NG-RAN node, such as a backhaul RAN node serving the MT component of the WAB node or another RAN node neighbouring or in the vicinity of the WAB node. For example, with reference to the communication system 500 shown in and described with respect to figure 5, the UE sending the notification may be the WAB-MT 541, the NG-RAN node sending the notification may be the WAB-gNB 542, the NG-RAN node receiving the notification may be the BH-gNB2 502, the AMF receiving the notification may be the AMF 511a. Also, the NG-RAN node sending the notification may be theBH-gNB2 502, the NG-RAN node receiving the notification may be the BH-gNBl 501, and the AMF receiving the notification may be the AMF 511a. The method 1000 as shown in and described with respect to figure 10 may be performed by software elements and / or hardware elements. The network entity sending or receiving the notification (e.g. UE, NG-RAN node or AMF) may be implemented in a network node 400 as shown in and described with reference to figure 4, with the method as shown in and described with respect to figure 10 being performed by an apparatus for the network entity (e.g. UE, NG-RAN node or AMF) including one or more processing units, such as the processing unit 402. At step 1002, after determining a status (e.g. current status or condition) of the backhaul link or a change in status or condition of the backhaul link (at step 1001), the network entity (e.g. UE or NG-RAN node) sends a notification of or information indicating backhaul link status or a backhaul link status change to an AMF or a NG-RAN node involved or associated with the backhaul link (i.e. another network entity which is involved with generating or forwarding traffic transmitted over or through this backhaul link). The notification may include the identification of the backhaul link and includes link quality information related to the radio conditions and / or the load of or congestion of the link. The notification of or information indicating backhaul link status or a backhaul link status change may be sent in a BH LINK STATUS message such as message 703, 713, 803, 813 as described above with reference to figures 7a, 7b, 8a, 8b. At step 1003, the UE or NG-RAN node may receive a response following the notification sent at step 1002. The response may include the identification of action(s) taken by the notified AMF or NG-RAN node based on information included in the received notification. For instance, when the AMF is a UE AMF and when the wireless backhaul link quality becomes below a predefined threshold, the AMF may prioritize the traffic to handle the mobility (handover) of UEs served by the WAB-gNB. The handover of UEs would indeed reduce the user plane and control plane traffic over the wireless backhaul link, which is used for the user plane traffic between the WAB-gNB and UE UPF(s), and the control plane traffic between the WAB-gNB and UE AMF(s). The AMF may also refrain from transmitting to the WAB-gNB status information like the NG protocol messages Overload Start, Overload Stop that do not contain useful information in this situation. When the NG-RAN node is the BH RAN node serving the WAB-MT and when the wireless backhaul link quality becomes below a predefined threshold during a certain time, the NG-RAN node may attempt to handover the WAB-MT toward a new BH RAN node with which the WAB-MT will benefit of another wireless backhaul link with a better quality. The response may be received in a BH LINK STATUS Response message such as message 705, 715, 805, 815 as described above with reference to figures 7a, 7b, 8a, 8b. At step 1004, the UE or NG-RAN node may apply action(s) taking into account the status of the backhaul link or change of status of the backhaul link and / or the information included in the response. When the NG-RAN node is the WAB-gNB serving UEs and when the wireless backhaul link quality becomes below a predefined threshold during a certain time, the NG-RAN node may attempt to handover the served UEs so as to reduce the user plane and control plane traffic over the wireless backhaul link. The NG-RAN can take this decision knowing that the UE AMF(s) will prioritize the transmission of messages related to the handover of the served UEs. When the UE is the WAB-MT and when the wireless backhaul link quality becomes below a predefined threshold during a certain time, the WAB-MT may prepare and send a measurement report to the BH RAN node knowing that a handover of the WAB-MT will be soon attempted by the BH RAN node. The measurement report indicates a list of cells detected by the WAB-MT in its vicinity and it can be used by the BH RAN node to select a suitable target cell for the WAB-MT. Referring now also to figure 11 is a flowchart of an example method 1100 for managing at network entity, such as an AMF (WAB or BH AMF and / or UE AMF(s) of a WAB node) or a NG-RAN node, such as a backhaul RAN node serving the MT component of the WAB node or another RAN node neighbouring or in the vicinity of the WAB node, the reception of a notification of or information indicating backhaul link status or a backhaul link status change. The network entity, such as an AMF or a NG-RAN node, receiving the notification is involved in or associated with the backhaul link (i.e. a network entity which is involved with generating or forwarding traffic transmitted over this backhaul link). For example, with reference to the communication system 500 shown in and described with respect to figure 5, the AMF may be the AMF 511a and the NG-RAN may be the BH-gNB2 502. The method 1100 as shown in and described with respect to figure 11 may be performed by software elements and / or hardware elements. The network entity (NG-RAN node or AMF) may be implemented in a network node 400 as shown in and described with reference to figure 4 with the method as shown in and described with respect to figure 11 being performed by an apparatus for the NG-RAN node or AMF including one or more processing units, such as the processing unit 402. At step 1101, the network entity (e.g. NG-RAN node or AMF) receives a notification of or information indicating backhaul link status or a backhaul link status change. The notification may include the identification of the backhaul link and link quality information related to the radio conditions and / or the load or congestion of the link. The notification of or information indicating backhaul link status or a backhaul link status change may be sent in a BH LINK STATUS message such as message 703, 713, 803, 813 as described above with reference to figures 7a, 7b, 8a, 8b. At step 1102, the AMF or NG-RAN node may determine and apply action(s) taking into account the status or change of status of the backhaul link as indicated in the received notification. At step 1103, the NG-RAN node or AMF may send a response following the notification received at step 1101. The response may include the identification of action(s) taken by the AMF or NG-RAN node at step 1102. The response may be sent in a BH LINK STATUS Response message such as message 705, 715, 805, 815 as described above with reference to figures 7a, 7b, 8a, 8b. By providing information indicating the status of the wireless backhaul link to one or more AMF entities and / or one or more NG-RAN nodes (which may include a backhaul RAN node serving the WAB node), core network entities (e.g. the UE AMF(s) and / or the BH AMF) and / or base station(s) of a Radio Access Network (RAN) can be informed about a wireless backhaul link status when a WAB node is wirelessly connected to the core network and the RAN through this wireless backhaul link and take appropriate action. For example, in a case where the information indicates the link status is degrading (e.g. congestion over the link has increased and has reached a threshold high level, and / or signal quality has decreased and has reached a threshold low level or RLF), the network devices or entities (such as the AMF(s), backhaul RAN nodes serving the WAB node) which are part of the wireless network and are associated with traffic transmitted over the wireless backhaul link (e.g. which generate and / or schedule and / or transmit traffic on the wireless backhaul link) may reduce the amount of data to be transmitted and / or prioritize the transmission of critical data so as to ensure continuity of service whilst taking account of the current link status (e.g. change in link status). In a case where the information indicates the link status is improving (e.g. congestion over the link has decreased to a threshold low level, and / or signal quality has increased to a threshold high level, or RLF has been recovered), the network devices or entities (such as the AMF(s), backhaul RAN nodes serving the WAB node) which are part of the wireless network and are associated with traffic transmitted over the wireless backhaul link (e.g. which generate and / or schedule and / or transmit traffic on the wireless backhaul link) may increase the amount of data to be transmitted and / or return to normal transmission of data taking account of the current link status (e.g. change in link status). It can be summarized that unlike the typical 5G NR scenario where the NG and Xn interfaces are operated over wired links, the WAB architecture implies that part of the NG / Xn links is wireless (i.e., the BH link between the WABMT and the BH-gNB is operated over the wireless Uu interface). Considering that the NG / Xn protocols have been designed to be operated over wired links, some countermeasures should be considered to guarantee the reliability of these interfaces when operated over a versatile wireless link, which is likely to experience link degradation or congestion. The WAB-gNB can be aware of the backhaul link quality status. However, the AMFs having established a NG connection with the WAB-gNB, and the NG-RAN nodes (other than the BH gNB) having established a Xn connection with the WAB-gNB, are not aware of the backhaul link quality status. Therefore, to help the mitigation of backhaul link degradation, the WAB-gNB should inform the connected AMFs and (WAB aware) NG-RAN nodes about any change in the status of the wireless backhaul link. For this purpose, the NG procedure RAN Configuration Update and the Xn procedure NG-RAN node Configuration Update may be enhanced to report the backhaul link quality status. While the present invention has been described with reference to examples and embodiments, it is to be understood that the invention is not limited to the disclosed examples and embodiments. It will be appreciated by those skilled in the art that various changes and modification might be made without departing from the scope of the invention, as defined in the appended claims. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used. In the preceding embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over, as one or more instructions or code, a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and / or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium. By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic 5 cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave may be included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non- 10 transient, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. 15

Claims

1. A method for use in managing link status of a wireless backhaul link in a wireless network including a Wireless Access Backhaul, WAB, node, the WAB node including a mobile termination, MT, component and a gNB component, the method at a network entity associated with the WAB node including:sending information for indicating a link status of a wireless backhaul link supporting one or more Radio Access Network, RAN, interfaces associated with the WAB node.

2. The method of claim 1, wherein the information for indicating a link status of a wireless backhaul link includes at least one of:link quality information for indicating an overall quality of the wireless backhaul link; radio link quality information for indicating radio quality of the wireless backhaul link; congestion information for indicating a level of congestion of the wireless backhaul link; information for indicating whether the wireless backhaul link status is stable;information for indicating whether a link quality of the wireless backhaul link is increasing or decreasing;cause information for indicating a cause for the link status of the wireless backhaul link.

3. The method of claim 2, wherein the link quality information has one of a plurality of values for indicating an overall level of quality of the wireless backhaul link, each value of the plurality of values representing a certain level of quality.

4. The method of claim 2 or claim 3, wherein the congestion information includes at least one of:downlink congestion information for indicating a level of congestion of the wireless backhaul link in downlink;uplink congestion information for indicating a level of congestion of the wireless backhaul link in uplink.

5. The method of any one of claims 2, 3 or 4, wherein in the case where the indicated link status represents radio link quality and / or congestion of the wireless backhaul link, the information for indicating whether a link quality of the wireless backhaul link is increasing or decreasing includes,for each of radio link quality and congestion level of the wireless backhaul link, information for indicating whether the respective radio link quality and congestion level is increasing or decreasing.

6. The method of any one of the preceding claims, wherein sending includes sending a message including the information for indicating a link status of the wireless backhaul link, wherein the message further includes at least one of:message type information for indicating the message includes information indicating a link status of the wireless backhaul link;information for identifying the network entity sending the message;information for identifying the wireless backhaul link.

7. The method of claim 6, wherein the information for identifying the wireless backhaul link includes at least one of:an identifier of a backhaul RAN node serving the WAB node;an identifier of the MT component of the WAB node;an identifier of the gNB component of the WAB node co-located with the MT component of the WAB node.

8. The method of any one of the preceding claims, wherein the network entity is one of: a Next Generation-RAN, NG-RAN, node of the wireless network;the MT component of the WAB node.

9. The method of any one of the preceding claims, wherein sending information for indicating a link status of the wireless backhaul link includes sending, to another network entity associated with the WAB node, information for indicating a link status of the wireless backhaul link.

10. The method of claim 9, wherein the other network entity is at least one of: one or more Access and Mobility Function, AMF, entities associated with the WAB node; one or more NG-RAN nodes associated with the WAB node.

11. The method of any one of the preceding claims, wherein in the case where the network entity sending the information indicating a link status of the wireless backhaul link is at least one of: the MT component of the WAB node; a backhaul RAN node serving the WAB node, the method further includes:receiving information identifying one or more AMF entities associated with the WAB node.

12. The method of claim 11, wherein the information identifying one or more AMF entities associated with the WAB node includes an identifier for each of one or more AMF entities associated with the WAB node.

13. The method of claim 11 or claim 12, wherein receiving information identifying one or more AMF entities associated with the WAB node includes receiving a message including the information, wherein the message further includes at least one of:message type information for indicating the message includes information identifying one or more AMF entities associated with the WAB node;information for identifying the network entity sending the message;information for identifying the wireless backhaul link.

14. The method of claim 13, wherein the information for identifying the wireless backhaul link includes at least one of:an identifier of a backhaul RAN node serving the WAB node;an identifier of the MT component of the WAB node;an identifier of the gNB component of the WAB node co-located with the MT component of the WAB node.

15. The method of any one of claims 11 to 14, wherein the information identifying one or more AMF entities associated with the WAB node is sent periodically or when the information identifying the one or more AMF entities is to be updated.

16. The method of any one of the preceding claims, wherein sending information indicating a link status of the wireless backhaul link includes sending, by a NG-RAN node, the information to at least one of:one or more Access and Mobility Function, AMF, entities associated with the WAB node; one or more other NG-RAN nodes neighbouring the WAB node.

17. The method of claim 16, wherein the NG-RAN node sending information indicating a link status of the wireless backhaul link is one of:a backhaul RAN node serving the MT component of the WAB node;the gNB component of the WAB node.

18. The method of any one of the preceding claims, wherein sending information indicating link status of the wireless backhaul link includes sending, by the MT component of the WAB node, the information to at least one of:a backhaul RAN node serving the WAB node;one or more Access and Mobility Function, AMF, entities associated with the WAB node.

19. The method of any one of the preceding claims, wherein sending the information for indicating a link status of a wireless backhaul link includes sending the information periodically or after detecting a change in link status of the wireless backhaul link.

20. The method of any one of the preceding claims, further comprising: receiving a response.

21. The method of claim 20, wherein in the case where the information for indicating a link status of the wireless backhaul link is sent to at least one AMF entity, the at least one AMF entity including at least one of: an AMF entity serving the MT component of the WAB node; and one or more AMF entities connected to the gNB component of the WAB node, receiving a response includes receiving a response from the at least one AMF entity, wherein the response includes information indicating an operation the respective AMF entity may perform after receiving the information for indicating a link status of the wireless backhaul link.

22. The method of claim 20, wherein in the case where the information for indicating a link status of the wireless backhaul link is sent by the MT component of the WAB node to a backhaul RAN node serving the WAB node, receiving a response includes receiving a response from the backhaul RAN node, wherein the response includes information indicating an operation the backhaul RAN node may perform after receiving the information for indicating a link status of the wireless backhaul link.

23. The method of claim 20, wherein in the case where the information for indicating a link status of the wireless backhaul link is sent by a NG-RAN node to another NG-RAN node, receiving a response includes receiving a response from the other NG-RAN node, wherein the response includesinformation indicating an operation the other NG-RAN node may perform after receiving the information for indicating a link status of the wireless backhaul link.

24. The method of any one of the preceding claims, further comprising:determining, by the network entity, a link status of the wireless backhaul link, wherein the information indicating a link status of the wireless backhaul link is based on the determined link status.

25. A method for use in managing link status of a wireless backhaul link in a wireless network including a Wireless Access Backhaul, WAB, node, the WAB node including a mobile termination, MT, component and a gNB component, the method at a network entity associated with a WAB node including:receiving information for indicating a link status of a wireless backhaul link supporting one or more Radio Access Network, RAN, interfaces associated with the WAB node.

26. The method of claim 25, wherein the information for indicating a link status of a wireless backhaul link includes at least one of:link quality information for indicating an overall quality of the wireless backhaul link;radio link quality information for indicating radio quality of the wireless backhaul link; congestion information for indicating a level of congestion of the wireless backhaul link; information for indicating whether the link quality of the wireless backhaul link is stable; information for indicating whether a link quality of the wireless backhaul link is increasing or decreasing;cause information for indicating a cause for the link status of the wireless backhaul link.

27. The method of claim 26, wherein the link quality information has one of a plurality of values for indicating an overall level of quality of the wireless backhaul link, each value of the plurality of values representing a certain level of quality.

28. The method of claim 26 or claim 27, wherein the congestion information includes at least one of:downlink congestion information for indicating a level of congestion of the wireless backhaul link in downlink;uplink congestion information for indicating a level of congestion of the wireless backhaul link in uplink.

29. The method of any one of claims 26, 27 or 28, wherein in the case where the indicated link status represents radio link quality and / or congestion of the wireless backhaul link, the information for indicating whether link quality of the wireless backhaul link is increasing or decreasing includes, for each of radio link quality and congestion level of the wireless backhaul link, information for indicating whether the respective radio link quality and congestion is increasing or decreasing.

30. The method of any one of the claims 25 to 29, wherein receiving includes receiving a message including the information for indicating a link status of the wireless backhaul link, wherein the message further includes at least one of:message type information for indicating the message includes information indicating a link status of the wireless backhaul link;information for identifying the network entity sending the message;information for identifying the wireless backhaul link.

31. The method of claim 30, wherein the information for identifying the wireless backhaul link includes at least one of:an identifier of a backhaul RAN node serving the WAB node;an identifier of the MT component of the WAB node;an identifier of the gNB component of the WAB node co-located with the MT component of the WAB node.

32. The method of any one of the claims 25 to 31, wherein receiving information for indicating a link status of the wireless backhaul link includes receiving, from another network entity, the information for indicating a link status of the wireless backhaul link, the other network entity is one of:a Next Generation-RAN, NG-RAN, node of the wireless network;the MT component of the WAB node.

33. The method of claim 32, wherein the NG-RAN node is one of:a backhaul RAN node serving the MT component of the WAB node;the gNB component of the WAB node.

34. The method of claim 33, wherein the network entity is one of: an Access and Mobility Function, AMF, entity associated with the WAB node; a NG-RAN node associated with the WAB node.

35. The method of any one of the claims 25 to 34, wherein in the case where the network entity receiving the information indicating a link status of the wireless backhaul link is a backhaul RAN node serving the WAB node, the method further includes:receiving information identifying one or more AMF entities associated with the WAB node.

36. The method of claim 35, wherein the information identifying one or more AMF entities associated with the WAB node includes an identifier for each of one or more AMF entities associated with the WAB node.

37. The method of claim 35 or claim 36, wherein receiving information identifying one or more AMF entities associated with the WAB node includes receiving a message including the information, wherein the message further includes at least one of:message type information for indicating the message includes information identifying one or more AMF entities associated with the WAB node;information for identifying the network entity sending the message;information for identifying the wireless backhaul link.

38. The method of claim 37, wherein the information for identifying the wireless backhaul link includes at least one of:an identifier of a backhaul RAN node serving the WAB node;an identifier of the MT component of the WAB node;an identifier of the gNB component of the WAB node co-located with the MT component of the WAB node.

39. The method of any one of the claims 25 to 38, further including in the case where the network entity is a backhaul RAN node serving the WAB node, sending, to one or more AMF entities associated with the WAB node or one or more other NG-RAN nodes neighbouring the WAB node, information for indicating the link status of the wireless backhaul link based on the information received at the backhaul RAN node.

40. The method of any one of the claims 25 to 39, wherein the information for indicating a link status of a wireless backhaul link is sent periodically or after detecting a change in link status of the wireless backhaul link.

41. The method of any one of the claims 25 to 40, further comprising: sending a response.

42. The method of claim 41, wherein in the case where the network entity is an AMF entity, sending a response includes sending, by the AMF entity, a response, wherein the response includes information indicating an operation the AMF entity may perform after receiving the information for indicating a link status of the wireless backhaul link.

43. The method of claim 41, wherein in the case where the network entity is a backhaul RAN node serving the WAB node, sending a response includes sending, by the backhaul RAN node, a response, wherein the response includes information indicating an operation the backhaul RAN node may perform after receiving the information for indicating a link status of the wireless backhaul link.

44. The method of claim 41, wherein in the case where the network entity is a NG-RAN node and the information for indicating a link status of the wireless backhaul link is received from another NG-RAN node, sending a response includes sending, by the NG-RAN node to the other NG-RAN node, a response, wherein the response includes information indicating an operation the NG-RAN node may perform after receiving the information for indicating a link status of the wireless backhaul link.

45. The method of any one of the preceding claims, wherein the one or more RAN interfaces include at least one of:a Xn interface associated with the gNB component of the WAB node;a NG interface associated with the gNB component of the WAB node;a NR Uu interface associated with the MT component of the WAB node.

46. A computer program comprising instructions which, when the program is executed by at least one processor unit, cause the at least one processing unit to carry out the method according to any one of claims 1 to 45.5 47. A computer-readable medium carrying a computer program according to claim 46.

48. An apparatus for a network entity, the apparatus comprising: one or more processing units configured to perform the method as recited in any one of claims 1 to 45.10

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